Preheat the oven to 375℉. Line a 12 tin muffin liner with 12 liners and set aside. If using tulip liners, line the tin with 8 tulip liners.
In a small bowl, make the streusel. Combine flour, white sugar, and cold cut up butter. Using your hands, mix it together until combined into a crumbly, streusel mixture. Set aside while you make the muffin batter.
3/4 cup all-purpose flour, 5 tbsp unsalted butter, 1/3 cup white sugar
In a large bowl, add in the flour, white sugar, and baking powder. Mix together.
3/4 cups white sugar, 1 1/2 cups all purpose flour, 1 3/4 tsp baking powder
Add in about 1/3 of the butter. Mix on low, and keep adding in the butter until you've added it all in and a crumbly texture forms. The key to a tender muffin is mixing as little as possible, so only mix until just combined!
3/4 cup unsalted butter
Add the eggs in one at a time, mixing in between each addition. Then, add in the vanilla. On low speed, continue mixing until just combined.
2 tsps vanilla extract, 3 large eggs
Mix in the milk, making sure it’s well incorporated. The batter will be smooth. If it is clumpy, this means your wet ingredients weren’t at room temperature before beginning.
1/3 cup milk
In the bowl with the blueberries, add 1-2 tsps of flour and gently toss around until evenly coated. The light coating of flour will absorb any extra liquid it may have before adding it into the mixing bowl.
1 1/2 cups fresh blueberries
Add the blueberries and mix in a few times.
Evenly divide the batter between the muffin liners. Sprinkle streusel on top.
Bake the muffins for 17-20 minutes if you're using regular liners, and 20-25 minutes if using tulip liners.
Cool, and enjoy! These muffins are the best.