• Preheat the oven to 375℉. Line the muffin tin with muffin liners and set aside. Chop the apples into small pieces and set aside.
  2 cups apples

For the streusel

• In a small bowl, make the streusel. Combine flour, white sugar, brown sugar, cinnamon, and cold cut up butter. Using your hands, mix it together until combined into a crumbly, streusel mixture. Set aside while you make the muffin batter.
  1/2 cup all-purpose flour, 1/4 cup light brown sugar, 1/4 cup white sugar, 1/4 tsp cinnamon, 3 tbsp unsalted butter

For the muffins

• In a medium-sized bowl, add the dry ingredients. Mix together and set aside to use later.
  2 cups all-purpose flour, 2 tsps baking powder, 1 tsp baking soda, 3/4 tsps cinnamon, 1/4 tsp salt
• In a large bowl, add the wet ingredients. Whisk together until combined and smooth.
  3/4 cups white sugar, 1/2 cup oil, 2 large eggs, 1 tsp vanilla, 1 cup sour cream
• Add the dry ingredients into the wet ingredients and using a spatula, mix together until a soft muffin batter forms. Once you see no flour streaks, stop mixing.
• Add in the apples and mix in. Do not over-mix!
  2 cups apples
• Evenly divide the batter between the muffin liners. Fill them halfway in tulip liners or to the top if using regular liners.
• Sprinkle a handful of streusel on top.
• Bake the muffins at 375°F for 22-28 minutes for tulip liners. If using regular liners, they will be done at the 18-22 minute mark. The muffins are ready when they bounce back at touch or a toothpick inserted comes out clean.