In a small bowl, mix together flour, baking powder, and salt.
In a separate medium-sized bowl, stir together melted butter and sugar. Add egg yolk, vanilla, and mik and whisk until completely blended. Stir wet ingredients into dry ingredients, gently fold in blueberries and pour into a buttered 10-ounce ramekin.
Bake for 15-20 minutes or until top is golden and center is completely cooked.
Remove ramekin from oven and place on a rack to cool slightly.
Enjoy with butter while still warm.
Notes
Use Room-Temperature Ingredients: For a uniform batter, make sure all your ingredients are at room temperature. This ensures even mixing and a better rise.
Verify Baking Powder Freshness: Make sure your baking powder is up-to-date for optimal fluffiness. Expired baking powder will lead to a flat, dense muffin.
Avoid Overmixing: Overmixing the batter can make your muffin too dense. Mix just until the flour is incorporated, aiming for a slightly lumpy texture.
Utilize a Baking Sheet: Put a baking sheet beneath the ramekin before placing it in the oven. This not only eases the cleanup if the batter overflows but also simplifies the process of taking the ramekin out of the oven.
Watch the Baking Time: Be vigilant to prevent overbaking, which leads to dryness and a dark crust. Your muffin is done when a knife or skewer comes out clean or with minimal crumbs.
Enjoy Freshly Baked: For the best flavor and texture, enjoy your muffin soon after it comes out of the oven.
Measure Your Ramekin: If your ramekin size is unclear, simply fill it with water and then pour the water into a measuring cup to determine its capacity.