• Preheat the oven to 375℉/190℃ and line a muffin tin with 12 liners. Set aside. You can use tulip liners or regular ones, I used tulip. Slice the peaches into small pieces and set aside as well.
  1 3/4 cups peaches chopped into small pieces*

For the streusel

• In a bowl, add the flour, butter, sugars, and oats. Mix together with your hands or a fork until a buttery streusel forms, then set in the fridge to chill as the batter is being made.
  1/2 cup all-purpose flour, 1/3 cup rolled oats, 1/4 cup white sugar, 1 tbsp brown sugar, 4 tbsp unsalted butter softened

For the muffins

• In a bowl, add the flour, oats, baking soda, baking powder, cornstarch, cinnamon, and salt. Stir to combine and set aside.
  1 1/2 cups all-purpose flour, 1 cup rolled oats, 1 tsp baking powder, 3/4 tsps baking soda, 1/2 tsp cinnamon, 1/4 tsp salt
• Into another large bowl, add the oil, sour cream, brown sugar, eggs, and vanilla. Whisk together for about a minute and combine.
  1/2 cup oil, 3/4 cups sour cream, 3/4 cups light brown sugar, 2 large eggs, 2 tsps vanilla
• Add the dry and wet ingredients together with a spatula gently just until a muffin batter forms. Do not over-mix!
• With the bowl with the peaches, add 1 tbsp of flour and evenly mix them around and coat them. Then add them into the bowl and mix a few times. Do not over-mix!
  1 3/4 cups peaches chopped into small pieces*
• Scoop evenly between the muffin liners. If making tulip liners, this recipe will make 12. If making regular muffins, fill them to the tops (this recipe will make more than 12 if using regular liners). Sprinkle a handful of streusel on top of each one.
• Bake the muffins. They will bake for 25-28 minutes in tulip liners, and 20-25 minutes in regular liners. The muffins are ready when a toothpick inserted in the middle comes out clean.
• Allow to cool, and enjoy!