Ingredients

• 2 sticks Butter (1/2 pound or 8 ounces) room temperature, see notes
• 2 cups Granulated Sugar
• 4 Eggs large, room temperature
• 2 Tbsp Lemon Zest
• 2 Tbsp Grapefruit Zest
• 2 Tbsp Lime Zest
• 2 Tbsp Orange Zest
• 3 cups Organic Unbleached White All-Purpose Flour
• OR Gluten Free 1-to-1 Baking Flour
• ½ tsp Baking Powder
• ½ tsp Baking Soda
• 1 tsp Sea Salt
• ¼ cup fresh squeezed Grapefruit Juice
• ½ cup fresh squeezed orange juice
• ¾ cup Mascarpone Cheese room temperature
• 1 tsp Vanilla Extract

• 1 ½ cups Powdered Sugar
• 1–2 Tbsp fresh squeezed orange juice

Instructions

1. Preheat oven to 350°F. Grease two standard loaf pans and line with parchment paper.
2. Sift together flour, baking powder, baking soda and salt. Set aside.
3. In the bowl of an electric mixer fitted with the paddle attachment, cream butter and granulated sugar until light and fluffy (4–5 minutes). Add eggs one at a time, incorporating after each addition, then add zests and mascarpone cheese.
4. Alternate adding dry ingredients with juice and vanilla in three rounds, beginning and ending with the dry ingredients. Scrape down the sides of the bowl.
5. Divide batter evenly between prepared pans, smooth the tops and bake for 50–60 minutes, or until a cake tester comes out clean.
6. Let cool in pan for about 10 minutes, then transfer to a rack to finish cooling.
7. Make the glaze: sift powdered sugar into a bowl, then add 1–2 tablespoons fresh squeezed juice and whisk until smooth. Drizzle over the cake after it cools.