Preheat oven to 400°F. In a large mixing bowl, beat 1/2 cup softened butter with an electric mixer on medium to high speed for 30 seconds. Beat in 1/4 cup sugar, 1/2 teaspoon baking powder, and 1/4 teaspoon salt until combined. Beat in 1 egg yolk. Add 1 1/2 cups all-purpose flour; beat until combined. (Mixture will be crumbly). Work dough mixture with your hands just until mixture holds together. Press the mixture on the bottom and 1 1/2 inches up the side of an 9-inch springform pan. Bake about 12 minutes or until edges of crust are lightly browned. Cool on wire a rack while preparing filling.