1/2 cup (115g) unsalted butter, softened to room temperature
1/2 cup (100g) packed light or dark brown sugar
1/4 cup (50g) granulated sugar
2 large eggs, at room temperature
1/2 cup (120g) yogurt, at room temperature
2 teaspoons vanilla extract
1 and 3/4 cups (220g) all-purpose flour
1 teaspoon baking soda
1 teaspoon baking powder
1 teaspoon ground cinnamon
1/2 teaspoon salt
1/4 cup (60ml) milk (any kind), at room temperature
1 and 1/2 cups peeled, chopped apple (2 small apples)
1 cup (120g) confectioners' sugar
3 Tablespoons (45ml) heavy cream (or milk for a less creamy texture)
1/2 teaspoon vanilla extract
In abowl, combine the two sugars, the cinnamon, and melted butter. Stir in the flour. The crumb topping will be thick and crumbly. Set aside.
Preheat oven to 425°F. Spray a 12-count muffin pan with nonstick spray. Set aside. *See note about jumbo size muffins.
Beat the butter and both sugars together on high speed until smooth and creamy, about 2 minutes. Scrape down the sides and bottom of the bowl as needed. Add the eggs, yogurt, and vanilla extract. Beat on medium speed for 60 seconds increase high speed until the mixture is combined and uniform in texture. Scrape excess down the sides and bottom of the bowl as needed.
Whisk in flour, baking soda, baking powder, cinnamon, and salt together in a medium bowl. Then, add the dry ingredients into the wet ingredients, add the milk and apple, and mix until combined.
Add the batter into each cup. Press a handful of the crumb topping into the top of each; crumble it with your hands to make larger chunks.
Bake for 5 minutes at 425°F. Then, lower the oven temperature to 350°F and bake for 15-17 more minutes or until a toothpick inserted in the center comes out clean. Total cooking time should be about 20-22 minutes.
Make the glaze: whisk all ingredients together and drizzle over hot muffins.