Ingredients
Blueberry Jam
- 1 ½ cups frozen blueberries
- 2 tablespoons white sugar
- 1 teaspoon lemon juice
Cupcakes
- 1 ¾ cups all-purpose flour
- 2 teaspoons baking powder
- ½ teaspoon salt
- 1 cup white sugar
- ½ cup unsalted butter, softened
- 2 large eggs, at room temperature
- 3 tablespoons lemon juice
- 1 ½ tablespoons lemon zest
- ½ teaspoon vanilla extract
- ⅔ cup buttermilk, at room temperature
- 1 ½ cups frozen blueberries
- 1 tablespoon all-purpose flour
Frosting
- 1 cup unsalted butter, softened
- 2 teaspoons lemon zest
- 1 ½ teaspoons lemon juice
- ⅛ teaspoon salt
- 3 ½ cups powdered sugar
- 1 tablespoon heavy cream
Directions
- Combine frozen blueberries, sugar, and lemon juice for jam in a small pot over medium heat; bring to a simmer. Cook, stirring occasionally, until mixture has reduced and thickened, about 12 minutes. Remove from the heat.
- Pour mixture through a fine mesh sieve, pressing solids to extract as much jam as possible; you should have approximately 1/4 cup. Discard any solids and refrigerate jam until completely cool, at least 30 minutes.
- Preheat the oven to 350 degrees F (175 degrees C). Line 18 muffin cups with paper liners.
- Whisk flour, baking powder, and salt for cupcakes together in a small bowl.
- Cream sugar and butter together in a large bowl until light and fluffy. Beat in eggs, 1 at a time, mixing well after each addition. Mix in lemon juice, lemon zest, and vanilla until combined. Add flour mixture in 2 batches, alternating with buttermilk, beating batter just until combined after each addition; batter will be somewhat thick.
- Place frozen blueberries in a small bowl and toss with flour until coated. Add to the batter and fold to incorporate. Spoon batter into the prepared muffin cups, filling each one 3/4 full.
- Bake in the preheated oven for 20 minutes. Check to see if a toothpick inserted into the centers comes out clean, and continue to bake, if needed, for 4 to 8 more minutes. Cool in the pans for 5 minutes before removing to a wire rack to cool completely, about 20 minutes more.
- While the cupcakes are cooling, remove blueberry jam from the refrigerator. Measure out 1/4 cup for the frosting and reserve any extra for another use.
- Beat butter for frosting in a large bowl until creamy and smooth. Add 1 cup powdered sugar, lemon zest, lemon juice, and salt; beat until thoroughly combined. Add 1/4 cup blueberry jam and mix until combined. Add 1 cup powdered sugar and mix until smooth. Repeat with remaining 1 1/2 cups powdered sugar. Add heavy cream and beat until frosting is smooth and fluffy, 1 to 2 minutes more.
- Frost cooled cupcakes.
