In a medium bowl, sift together flour, baking powder, and salt. Set aside.
In a large bowl, cream together granulated sugar, brown sugar, and butter.
Mix in eggs and egg yolk.
Mix in vanilla extract, maple extract, and sour cream.
Mix the dry ingredients into the wet ingredients, alternating with the milk.
Once batter is combined and fluffy, stir in the pecan butter and 1/2 cup of the butter pecan chips (reserve the other 1/2 cup for the frosting)
Pour batter evenly into prepared pans and bake for 25-28 minutes or until a toothpick inserted into the center comes out clean (may need more or less time so check on it at the 25-minute mark)
Allow the cakes to cool in the pan until the pans are cool enough to touch, and then carefully, remove them from the pans and allow them to cool completely on a cooling rack.