½cup(1 stick or 113 g) unsalted butter, room temperature
¼cupsour cream (or Greek yogurt), room temperature
2large eggs, room temperature
1teaspoonpure vanilla extract
½cup(120 ml) milk, room temperature
1 ½cupsdiced apples, Granny Smith or Honeycrisp
Instructions
Preheat oven to 400° F. Prepare a muffin tin with paper liners and set aside.
Make the crumble by whisking together the flour, brown sugar, sugar and cinnamon. Pour in melted butter and mix until small clumps form. Set aside.
In a medium bowl, whisk together the flour, baking powder, salt and cinnamon. Set aside.
In a large bowl, use an electric mixer to beat together brown sugar, granulated sugar and butter together until light and fluffy. Add eggs, sour cream and vanilla, and mix until well combined. Scrape down sides and bottom of the bowl as necessary.
Add half the flour mixture and mix just until combined. Add the milk and mix again. Add remaining flour mixture and mix just until combined. Stir in diced apples by hand.
Divide batter among prepared muffin cups, filling each cup three-quarters full. Generously sprinkle crumble mixture over muffins (use all the streusel).
Bake at 400° F for 20 minutes or until a toothpick inserted in the center comes out with little to no crumbs. Allow muffins to cool in the pan for a few minutes before transferring to a wire rack to cool completely.
Notes
Apples: Granny Smith, Braeburn and Honeycrisp are best for baking.Store muffins in an airtight container at room temperature for 3 days.Freeze muffins in an airtight container for up to 1 month.