Preheat oven to 350°F. Grease a loaf pan and set aside.
Toss chopped pecans with melted butter and light brown sugar. Spread on a baking sheet and toast for 6 minutes, flipping halfway. Let cool.
Sift together flour, baking powder, and salt. Set aside.
Cream together granulated sugar, brown sugar, and softened butter until light and fluffy. Mix in eggs and egg yolk, then add vanilla extract, maple extract, and sour cream.
Gradually mix in the dry ingredients, alternating with milk, until smooth. Stir in the cooled toasted pecans.
Pour batter into the prepared loaf pan and bake for 50-55 minutes, or until a toothpick inserted in the center comes out clean. Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Cream together cream cheese and butter until smooth. Add powdered sugar and vanilla extract, mixing until fluffy. Fold in buttered pecan chips.
Once the loaf is cool, spread the frosting on top.