01 -
Set your oven to 375°F and line a 12-cup muffin tray.
02 -
Mix sugar, flour, and cinnamon in a small bowl. Pour in melted butter, then use a fork to stir until it forms clumps. Pop it in the fridge to chill.
03 -
In a large bowl, whisk together baking powder, flour, lemon zest, sugar, and salt.
04 -
Whisk together the egg, melted butter, and buttermilk in a separate bowl. If it looks odd, that's normal—don't worry!
05 -
Add wet ingredients into the bowl with the dry mix. Stir until barely mixed—it’ll look lumpy, and that’s fine.
06 -
With a gentle hand, fold the blueberries into the batter. Don’t overmix, or the batter might turn purple.
07 -
Scoop about 3 tablespoons of batter into each muffin liner, filling all 12 cups evenly.
08 -
Sprinkle the chilled crumb mixture over the batter on each muffin.
09 -
Bake for 28–30 minutes. Muffins are done when their tops are golden and spring back when touched lightly.
10 -
Let them cool completely for a couple of hours—they taste even better that way!