For the pancakes: Sift together the flour, baking powder, baking soda, and 1/2 teaspoon salt. In a separate bowl, beat the eggs slightly and add the buttermilk, milk, and melted butter. Add the wet ingredients to the dry ingredients and mix well, let sit for 20 minutes.
For the praline sauce: Meanwhile, prepare the topping while the pancake mixture is standing. Combine the sugar and cornstarch in a microwave-safe bowl. Stir in the water and add the butter. Microwave on high 3 minutes or until the mixture is slightly thickened, stir halfway through the cooking. Stir in the pecans. Set aside until ready to serve as a topping for the pancakes.
Heat a lightly oiled griddle or frying pan over medium-high heat. Pour or scoop the batter onto the griddle, using approximately 1/4 cup for each pancake. When bubbles appear place about 4 banana slices on top of pancake, then cover the bananas with about 2 to 4 tablespoons pancake batter. Flip when the edges seem dry and cook on the other side until cooked through.
Spoon the warm praline sauce on top of a stack and dust with powdered sugar.
Cook's Note: The key to success is taking the time to let the praline sauce turn just the right color.