In a mixing bowl combine flour, pecans, sugar, baking powder and salt. In another bowl beat the egg yolks and vanilla slightly. Beat the milk and 1/2 cup melted butter into the egg mixture. Fold the flour mixture into the egg mixture. Stir until combined yet still slightly lumpy. In a small bowl beat the egg whites until stiff peaks form. Gently fold beaten egg whites into batter, leaving little fluffs of egg whites. Pour 1 cup batter onto grids of a preheated, lightly greased waffle iron. Close lid quickly: do not open during baking. Bake according to the manufacturer's directions for the waffle iron. In a saute pan, melt the remaining 2 tablespoons butter. Add the pecan pieces and saute until golden, about 2 to 3 minutes. Add the banana slices and syrup and bring the liquid to a simmer.