Preheat oven to 350°F and grease a 9x13-inch baking pan thoroughly with butter or cooking spray.

In a large mixing bowl, combine butter pecan cake mix, coconut pecan frosting, eggs, oil, and milk. Beat with electric mixer on medium speed for 2 minutes until smooth and well-blended.

Fold in 1/4 cup chopped toasted pecans, reserving the rest for the topping. Pour batter into prepared pan and spread evenly.

Bake for 30-40 minutes until toothpick inserted in center comes out clean and edges pull away from pan slightly. Check at 30 minutes.

Remove cake from oven and cool for 10 minutes. Use handle end of wooden spoon to poke holes all over surface, about 1 inch apart, going deep but not through bottom.

For praline sauce: In saucepan over medium heat, melt butter. Add sweetened condensed milk and stir until combined. Bring to gentle simmer, then remove from heat.

Stir in remaining chopped pecans and vanilla extract. Pour sauce slowly over warm cake, letting it soak into holes.

Let cake cool completely before serving. Refrigerate until ready to serve for best texture and flavor.