Preheat the oven to 375 degrees F (190 degrees C). Grease a 10x15-inch baking pan.

Bring butter and water to a boil in a large saucepan. Remove from the heat; stir in flour, white sugar, eggs, sour cream, almond extract, salt, and baking soda until smooth. Pour the batter into the prepared baking pan.

Bake in the preheated oven until the cake is lightly golden and a toothpick inserted into the center comes out clean, 20 to 22 minutes. Cool for 20 minutes.

While the cake cools, prepare the frosting. Bring butter and milk to a boil in a saucepan. Remove from the heat; stir in confectioners’ sugar and almond extract until smooth, then stir in pecans. Spread the frosting over the warm cake immediately, as it sets quickly. Garnish with additional chopped pecans, if desired.