• Line a muffin tin with liners and set aside. Melt the butter and prepare to measure the rest of your ingredients as it cools.

For the streusel

• Combine flour, white 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 tsp cinnamon, 6 tbsp butter, 1/3 cup white sugar, 3/4 cup all-purpose flour

For the muffins

• In a medium-sized bowl, add the flour, baking powder, baking soda, cornstarch, and salt. Mix together and set aside.
  2 1/2 cups all-purpose flour, 3 tsp baking powder, 1 tsp baking soda, 1/2 tsp salt, 1 tbsp cornstarch
• In a large bowl, add oil, butter, buttermilk, egg, egg yolk, and vanilla. Whisk until well combined. It’s okay if it is clumpy.
  1/2 cup butter, 3 tbsp oil, 1 egg, 1 egg yolk, 1 cup buttermilk*, 1 tbsp vanilla, 1 cup white sugar
• Add in the dry ingredients and using a spatula, slowly fold until a soft muffin batter forms. Mix until JUST combined.
• In the bowl with the diced peaches, add 1-2 tsps of flour and gently toss around until evenly coated. The light coating of flour will absorb any extra liquid it may have before adding it into the mixing bowl.
  2 cups diced peaches
• Add the peaches and mix in a few times.
• Evenly divide the batter between the muffin liners. Sprinkle streusel on top.
• Bake the muffins at 425°F for 5 minutes, then turn down to 375°F and bake for an additional 15-17 minutes. The muffins are ready when a toothpick inserted comes out clean.
• Enjoy!!