In a small bowl, stir together the butter and sugar until well blended.
Add in the egg yolk and vanilla extract and stir until combined.
In a separate small bowl, whisk together flour, cinnamon, baking powder, and salt. Pour into egg mixture and stir to combine.
Stir in the milk and fold in the blueberries.
Pour the batter into a 10-ounce ramekin lightly greased with butter or oil.
Place the ramekin on a baking sheet and bake for 30-35 minutes or until the top is golden brown. The cake is cooked through if the tip of a sharp knife inserted in the center comes out clean.
To make the glaze
In a small bowl, whisk together powdered sugar, milk, and vanilla until smooth. Drizzle over cooled coffee cake.Note: If the glaze is too thick, add a small amount of milk or cream. If the glaze is too runny, whisk in additional powdered sugar until you reach your desired consistency.
Notes
Preparation is Key: Before starting, assemble all your ingredients and familiarize yourself with the recipe steps. This ensures a smooth and efficient baking process.
Berry Varieties: Don't hesitate to experiment with different berries. Cherries, raspberries, blackberries, or a mix can be fantastic alternatives to blueberries, offering new flavors and textures.
Lemon Blueberry Twist: For a zesty variation, add 1/8 teaspoon of lemon zest to your batter. Replace vanilla with lemon juice in both the cake and the glaze for a refreshing lemon blueberry flavor.
Cinnamon Coffee Cake Option: For a simpler yet equally delicious version, skip the fruit and focus on cinnamon. This creates a classic cinnamon coffee cake, perfect for those who prefer a less fruity dessert.