Preheat your oven to 400°F and get your muffin tin ready—either give it a light spritz of nonstick spray or pop in some paper liners. Set it aside for now.

For the streusel topping, grab a small bowl and whisk together the Bisquick mix and brown sugar. Then, work in the butter with a pastry blender (or your fingers!) until it turns into a crumbly mixture. Set that aside—it’s going to be the star of your muffins!

In a large mixing bowl, whisk together the milk, melted butter, egg, sugar, and vanilla extract until everything is nice and smooth. Gently stir in the Bisquick mix just until it’s combined—don’t overmix! Finally, fold in those juicy blueberries.

Using a cookie scoop (about 3 tablespoons works great), evenly divide the batter into the prepared muffin tin. Sprinkle the crumbly streusel topping generously over each one.

Bake the muffins for 15 minutes, or until a toothpick poked into the center comes out clean. Let them cool in the tin for a few minutes before transferring them to a wire rack to cool completely.

Enjoy these warm with a cup of coffee or tea!