Preheat your oven to 350°F (175°C). Grease a 9-by-13-inch baking pan with butter or nonstick cooking spray. For easier removal, you can line the bottom with parchment paper, leaving a little overhang along the sides.

Although Texas sheet cakes are traditionally made in larger, shallow pans, a 9-by-13-inch pan produces a thicker cake that works particularly well for a home-style dessert with caramel and pecans.

If you prefer a thinner, more traditional sheet cake, use a larger rimmed sheet pan, approximately 13 by 18 inches, and begin checking for doneness earlier. The baking time will vary depending on the pan size and batter depth.

Measure the flour, cocoa powder, sugar, baking soda, baking powder, and salt before starting. Sifting the cocoa powder can help eliminate lumps and distribute the chocolate flavor evenly.

Step 2: Make the chocolate cake batter

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, cocoa powder, baking soda, baking powder, and salt. Make sure the dry ingredients are evenly combined.

Place the butter and water in a medium saucepan over medium heat. Stir gently until the butter melts and the mixture becomes hot. Whisk in the cocoa powder if you prefer to bloom it in the liquid, allowing the chocolate flavor to develop.

Remove the saucepan from the heat and let the mixture cool slightly. Pour it into the dry ingredients and stir until combined.

Add the buttermilk, eggs, and vanilla extract. Whisk or beat gently until the batter is smooth and free of large lumps. Avoid overmixing, because excessive mixing can make the finished cake dense.

The batter should be relatively thin compared with many traditional cake batters. This is normal for a moist chocolate sheet cake.

Pour the batter into the prepared baking pan and spread it evenly into the corners.

Step 3: Bake the chocolate sheet cake

Place the pan in the preheated oven and bake for approximately 25–35 minutes for a 9-by-13-inch pan. The exact time depends on your oven, pan material, and batter depth.

Begin checking the cake around the 25-minute mark. Insert a toothpick into the center. If it comes out clean or with a few moist crumbs, the cake is ready. If it comes out covered in wet batter, continue baking for several minutes before checking again.

Avoid overbaking. A chocolate cake that stays in the oven too long can become dry, especially around the edges.

Remove the cake from the oven and place the pan on a heatproof surface. Allow it to rest briefly before adding the caramel pecan layer. The cake should still be warm enough for the topping to spread easily, but it should not be so hot that the caramel becomes excessively runny.

Step 4: Prepare the caramel pecan topping

Place the unwrapped caramel candies, milk or heavy cream, and butter in a small saucepan. Heat over low heat, stirring frequently, until the caramels melt and the mixture becomes smooth.

Keep the heat gentle. Caramel can scorch if it is heated too quickly, and high heat may cause the mixture to become unpleasantly thick.

If the caramel seems too thick to spread, add another teaspoon of milk or cream at a time until it reaches a smooth, spoonable consistency.

Stir in most of the chopped pecans, reserving a small handful for decorating the top of the cake.

Spoon the caramel pecan mixture over the warm chocolate cake. Spread it gently with a spatula, leaving a small border around the edges if you prefer a neater appearance.

For a stronger turtle candy flavor, drizzle a little additional caramel sauce across the surface. Do not add too much liquid caramel, as an overly thick layer may make the cake difficult to slice.

Step 5: Prepare the chocolate frosting

In a medium saucepan, melt the butter over low heat. Stir in the cocoa powder until the mixture is smooth and fragrant.

Add the milk and continue stirring until the mixture is well combined. Remove the saucepan from the heat.

Gradually whisk in the powdered sugar, adding it in batches to prevent lumps. Stir in the vanilla extract and a pinch of salt.

The frosting should be smooth, glossy, and thick enough to coat the cake while remaining easy to spread. If it is too thick, add a small amount of milk. If it is too thin, add a little more powdered sugar.

For a traditional Texas sheet cake texture, pour the warm chocolate frosting over the cake while the frosting is still fluid. Spread it gently over the caramel pecan layer.

Some of the caramel may blend slightly with the frosting, creating a delicious marbled effect. This is perfectly fine and adds to the homemade appearance.

Step 6: Decorate with pecans and caramel

Sprinkle the reserved chopped pecans over the chocolate frosting before it sets. For additional flavor, lightly toast the pecans in a dry skillet for a few minutes, stirring frequently and allowing them to cool before using.

Drizzle extra caramel sauce over the cake in thin lines. You can also add melted chocolate or chocolate shavings for a more decorative finish.

If you enjoy the sweet-and-salty combination, add a very light sprinkle of flaky sea salt. The salt complements the chocolate and caramel without making the dessert taste overly salty.

For a festive presentation, arrange a few pecan halves across the top before the frosting firms.

Step 7: Allow the cake to cool and serve

Let the Texas Turtle Sheet Cake cool until the frosting has set sufficiently for clean slicing. Depending on the temperature of your kitchen and the thickness of the frosting, this may take approximately 30–60 minutes.

For especially neat slices, allow the cake to cool completely. Use a sharp knife and wipe the blade between cuts.

Serve the cake at room temperature for the softest texture and richest flavor. If you prefer a firmer caramel layer, refrigerate the cake briefly before slicing, then allow individual portions to sit at room temperature for a short time before serving.

Enjoy each slice with its combination of moist chocolate cake, gooey caramel, crunchy pecans, and rich chocolate frosting.