In a bowl fit with a mixer, beat together butter, peanut butter and vanilla extract. Beat in both sugars, salt and baking powder. Gradually mix in flour and continue mixing until well incorporated. Beat in eggs, one at a time. Roll into 1 1/2 in balls and slightly flatten with fork making a crisscross. Top cookies with streusel topping and bake for 10-13 minutes. Let cookies completely cool before moving to cooling rack.