Individual Lemon Blueberry Trifles

Butter a 9-inch cake pan. Preheat oven to 300 ºF (150 ºC). In a small bowl, whisk together flour, baking powder, baking soda, and salt. In a large bowl, cream together butter and sugar. Add egg and beat well. Beat in vanilla and lemon extracts. Add half of the dry ingredients to the wet ingredients and mix. Add buttermilk and beat. Add remaining dry ingredients and mix just until combined. Pour batter into prepared pan, smooth it out, and bake in preheated oven until lightly browned and a toothpick inserted in the center comes out clean, about 30 minutes. Cool completely before making the trifles.