• Preheat the oven to 350℉/176℃. Line a 9x9 baking tray with parchment paper and set aside. Slice the peaches into smaller pieces (see photo above for reference) and set aside. Melt the butter and allow it to cool as the rest of the ingredients are being measured.
  1/4 cup butter, 2 large peaches

For the streusel

• In a bowl, add the white sugar, butter, and flour. Mix together with your hands until a crumbly streusel forms. Place in the fridge to chill as the cake batter is being made.
  1 cup all-purpose flour, 6 tbsp unsalted butter, 1/3 cup + 1 tbsp white sugar

For the cake

• In a bowl, add the dry ingredients; flour, cornstarch, baking soda, baking powder, salt, and cinnamon. Stir to combine and set aside.
  1 3/4 cups all-purpose flour, 1 1/4 tsp baking powder, 1/2 tsp baking soda, 1 tbsp cornstarch, 1/4 tsp cinnamon, 1/2 tsp salt
• In a large bowl, add the melted butter, oil, and white sugar. Whisk for 2-3 minutes until well combined.
  2/3 cups white sugar, 1/3 cup oil, 1/4 cup butter
• Add in the eggs and vanilla. Continue whisking.
  2 large eggs, 1 tbsp vanilla
• Whisk in the sour cream, scraping the bowl as needed.
  1/2 cup sour cream
• Add in the dry ingredients, and gently with a spatula mix it together to form a soft cake batter.
• Into the bowl with the peaches, sprinkle 1 tbsp of flour. Mix around and evenly dust the peaches in the flour.
  2 large peaches
• Add the peaches into the batter and stir to combine, don't over-mix!
• Transfer the batter into the prepared pan and spread evenly. Add a couple extra peach slices on top (optional). Sprinkle streusel on top evenly.
• Bake for 40-50 minutes, or until a toothpick inserted comes out clean.
• Allow to cool, slice, and enjoy!