Pre-heat oven to 375F (190C). Grease and flour well a 12 cup muffin pan.
In a medium pot over medium heat melt the butter, remove from the heat and let cool slightly, add the sugar, sour milk, egg and vanilla and whisk until combined well.
Gently stir in the flour and soda, just until combined, about 15-16 stirs. Remember do not over combine. The batter will be lumpy. Then gently fold in the berries and chocolate chips.
Fill the muffin tin with the batter almost to the top. Top with the streusel mixture, bake 25-30 minutes, (check for doneness with a toothpick).
Let the muffins cool 10-15 minutes, before removing from the pan to a wire rack to cool completely. Enjoy!
STREUSEL TOPPING
In a medium bowl mix together the flour and sugar add the melted butter and stir with a fork until mixture resembles small crumbs (the size of peas), stir in chocolate chips.
Notes
Remember don’t overmix the batter. Over-mixing the batter can make the muffins tough and they may not bake as evenly.
You can use either fresh or frozen blueberries in this recipe. If you use frozen, make sure they are thawed first. Wash and dry fresh berries before folding into the batter.
Cupcake liners are not required for this recipe. Simply grease and flour your muffin pan well before adding the batter. You can, however, use liners if you like. Liners make removal easy, and they also come in different colors, which can be nice to use to coordinate if you have a special event.
Let the muffins cool completely then store in an airtight container or bag, store them at room temperature. Muffins should last up to 2-3 days or 7 days in the fridge.Freshly baked completely cooled muffins can also be stored in the freezer, be sure to place in an air tight container or freezer bag. They will keep up to 3 months.