Ingredients:

  • 1/2 cup All-Purpose Flour (for crumble)
  • 1/4 cup Granulated Sugar (for crumble)
  • 1/4 cup Toasted Hazelnuts (roughly chopped, for crumble)
  • 3 tablespoons Unsalted Butter (cold, cubed, for crumble)
  • Pinch of fine Sea Salt (for crumble)
  • 1/2 cup Mascarpone Cheese (room temperature, for swirl)
  • 2 tablespoons Powdered (Icing) Sugar (for swirl)
  • 1/2 teaspoon Vanilla Extract (for swirl)
  • 1 3/4 cups All-Purpose Flour (for batter)
  • 3/4 cup Unsweetened Cocoa Powder (Dutch-processed, for batter)
  • 1 teaspoon Baking Soda
  • 1/2 teaspoon Baking Powder
  • 3/4 teaspoon Fine Sea Salt
  • 3/4 cup Granulated Sugar
  • 2 Large Eggs (room temperature)
  • 1/2 cup Vegetable Oil
  • 1/2 cup Buttermilk (room temperature)
  • 1 teaspoon Vanilla Extract
  • 1/2 cup Hot Water or Hot Coffee
  • 1/2 cup Chocolate Chips (semi-sweet or dark)

Instructions:

  1. Preheat oven to 400°F (200°C). Line standard 12-cup muffin tin with paper liners.
  2. Make the Crumble: In a bowl, combine dry crumble ingredients (flour, sugar, salt). Cut in the cold butter using fingertips until coarse crumbs form. Stir in hazelnuts. Set aside in the fridge.
  3. Prepare Mascarpone Swirl: Gently whisk together mascarpone, powdered sugar, and vanilla extract until just smooth. Do not overmix. Set aside.
  4. Whisk Dry Ingredients (Muffins): In a large bowl, whisk together the batter flour, cocoa powder, baking soda, baking powder, salt, and granulated sugar.
  5. Combine Wet Ingredients (Muffins): In a separate bowl, whisk eggs, oil, buttermilk, and vanilla extract until combined.
  6. Combine Wet and Dry: Pour the wet ingredients into the dry ingredients. Fold gently with a spatula until just combined—a few streaks of flour are acceptable; do not overmix.
  7. Bloom the Cocoa: Carefully whisk the hot water or hot coffee into the batter until smooth. Fold in the chocolate chips.
  8. Fill Tins: Divide the batter evenly among the 12 muffin cups, filling each about two-thirds full.
  9. Swirl & Top: Drop small teaspoons of the mascarpone mixture onto the center of each muffin. Use a toothpick to gently swirl the mascarpone into the batter once or twice. Sprinkle generously with the chilled hazelnut crumble.
  10. Bake: Bake for 5 minutes at 400°F (200°C). Then, reduce the oven temperature to 375°F (190°C) and bake for an additional 15–19 minutes, or until a tester comes out clean.
  11. Cool: Let muffins cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.