Step 1

Preheat the oven to 375 degrees F.  Line a muffin tin with paper liners.

Step 2

Start with the streusel crumb topping. In a small bowl, whisk to combine the flour, sugar, and cinnamon. Pour in the melted butter and mix with a fork until crumbs form. Chill in the refrigerator while you continue with the recipe.

Step 3

For the muffin batter, in a large bowl, whisk to combine the flour, sugar, baking powder, salt and citrus zest.

Step 4

In another large bowl, whisk to combine the melted butter, egg, and buttermilk. It's fine if it looks curdled or lumpy.

Step 5

Add the wet ingredients to the dry, and stir just enough to bring the batter together. It will be thick and lumpy, and that's fine. Take care not to overstir, which can make your muffins tough.

Step 6

Dump in the blueberries, and fold them in gently, just enough to distribute them somewhat evenly. Take care not to stir too much, or your batter will turn purple.

Step 7

Use a large 3-Tbsp cookie scoop and scoop slightly overfilled portions evenly into the 12 lined muffin wells.

Step 8

Remove the crumb topping from the fridge and break up the crumbs with your fingertips, sprinkling the topping onto each of the muffin batter scoops.

Step 9

Bake for 28-30 minutes, until the crumbs are golden brown. To make sure they are done inside, I gently press my fingertip in the top center of the muffin. It should spring back to the touch.

Step 10

They can be enjoyed warm out of the oven, but I personally find the flavor to be at its best after they've cooled for about 2 hours. Enjoy!