Preheat your oven to 350°F, which is about 175°C. Grease a 9x13-inch baking pan generously with butter or nonstick spray.
In a large bowl, combine the yellow cake mix, water, vegetable oil, and eggs. Mix according to the package instructions until the batter is smooth and free of lumps. Fold in 1/2 cup of chopped pecans.
Pour the batter into the prepared pan. Use a spatula to spread it evenly. Bake for 28 to 32 minutes. The cake is ready when a toothpick inserted in the center comes out clean.
While the cake bakes, prepare the praline filling. In a medium saucepan, combine sweetened condensed milk, unsalted butter, and brown sugar. Cook over medium heat, stirring constantly to prevent scorching. The mixture should thicken and turn a golden brown color after about 5 to 7 minutes.
Remove the saucepan from the heat. Stir in the vanilla extract and 1/2 cup chopped pecans. The filling will continue to thicken slightly as it cools.
When the cake comes out of the oven, let it cool for exactly 5 minutes. Using the handle of a wooden spoon, poke holes all over the surface. Space the holes about 1 inch apart. Make sure the holes go deep but not all the way through the bottom.
Pour the warm praline filling over the warm cake. Use a spatula or the back of a spoon to guide the filling into the holes. Allow the cake to cool completely at room temperature.
For the frosting, beat the softened butter in a large bowl until creamy. Gradually add the powdered sugar, alternating with the heavy cream. Beat in the vanilla extract and salt. Continue beating until the frosting is smooth and fluffy.
Spread the frosting evenly over the completely cooled cake. An offset spatula works beautifully here.
Sprinkle the remaining 1/2 cup chopped pecans over the frosting. Finish with a generous drizzle of caramel sauce.
Refrigerate the cake for at least 2 hours before serving. This rest time allows the praline filling to set and the flavors to meld.