• Line your jumbo muffin tin with liners and set aside. Melt the butter and prepare to measure the rest of your ingredients as it cools.
  1/4 cup unsalted butter

For the streusel

• In a small bowl, make the streusel. Combine flour, white sugar, 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.
  3/4 cups all-purpose flour, 1/3 cup white sugar, 6 tbsp unsalted butter

For the muffins

• Mix together your dry ingredients and set aside to use later.
  2 1/2 cups all-purpose flour, 2 1/2 tsps baking powder, 1 tsp baking soda, 1/4 tsp salt, 2 tsps cornstarch
• In a large bowl, whisk melted and cooled butter, white sugar, eggs, buttermilk, oil, and vanilla. Whisk until combined.
  1/4 cup unsalted butter, 1/4 cup oil, 2 large eggs, 1 cup buttermilk*, 1 tbsp vanilla, 1 cup white sugar
• Add the dry into the wet ingredients. Using a spatula, stir until just combined. Don't over-mix!
• Toss in the mini chocolate chips and fold a few more times to evenly distribute them.
  1 cup mini chocolate chips
• Evenly divide your muffin batter between your liners. Make sure they are about 3/4s of the way full, no more or else they will overflow. This recipe made 8 jumbo muffins for me, but depending on the size of your jumbo pan it can make more or less.
• Bake the muffins at 425°F for 5 minutes, then turn down to 375°F and bake for an additional 20-25 minutes. The muffins are ready when a toothpick inserted comes out clean.
• These muffins are best eaten fresh or the next day. They stay fresh at room temperature for a few days, or in the refrigerator in an airtight container for up to 1 week!