Streusel Topping
In a small mixing bowl, add the flour, butter, both sugars, salt, and cinnamon. Cut the butter into the flour using a fork or your fingers, until you have small pea size pieces of streusel. Tip - With this amount of streusel, it is easier to use your fingers to mix the streusel.
3 tablespoons all-purpose flour,1 ½ tablespoons unsalted butter, cold and cut into cubes,1 ½ tablespoons light brown sugar,2 teaspoons granulated sugar,1/4 teaspoon ground cinnamon,pinch salt
Stir in the reserved diced apples. Refrigerate the streusel topping until ready to use.
1 ½ tablespoons diced apples
Apple Pumpkin Muffins
Preheat oven to 425F degrees and adjust oven rack to the middle position. Line the muffin pan with 4 muffin liners.
In a medium mixing bowl add the sour cream, pumpkin, juice , both sugars, egg yolk, and vanilla extract. With a fork, mix until combined and smooth. Stir in the remaining apple cubes.
1 ½ tablespoons full fat sour cream, room temperature,5 tablespoons pure canned pumpkin,1 tablespoon apple juice,3 tablespoons granulated sugar,2 tablespoons light brown sugar,1 large egg yolk, room temperature,1/2 teaspoon vanilla extract,1/2 cup fresh apple, cut into small cubes
In a small mixing bowl, whisk together the flour, baking soda, salt, and pumpkin pie spice. Sprinkle the dry ingredients over the wet ingredients. Use a spatula to fold the dry ingredients into the batter until no dry streaks remain. Do not overmix the batter, otherwise the muffins may turn out chewy.
1/2 cup, plus 1 tablespoon all-purpose flour,1/4 teaspoon baking soda,3/4 teaspoon pumpkin pie spice,1/8 teaspoon salt
Evenly scoop the batter into the prepared muffin liners. Top each muffin with equal portions of the streusel topping.
Bake at 425F degrees for 5 minutes. The quick time at high heat makes the muffin tops puff up. Then reduce the heat to 350F degrees and bake for an additional 11 to 13 minutes, or until a toothpick inserted in the middle comes out mostly clean.
Cool the muffins in the pan set on a wire cooling rack for 10 minutes, then transfer the muffins to the wire rack to cool completely.
The muffins can be stored covered at room temperature for 3 to 5 days.