Blueberry Bundt Cake

Ingredients

• 3 cups flour
• 1 ½ teaspoons baking powder
• ¾ teaspoon baking soda
• 1 teaspoon salt
• ½ teaspoon ground cinnamon
• ¾ cup buttermilk
• 2 teaspoons grated lemon zest, plus 3 tablespoons juice
• 2 teaspoons vanilla
• 3 large eggs plus 1 large yolk, room temperature
• 18 tablespoons (2 ¼ sticks) unsalted butter, softened
• 2 cups sugar
• ¾ cup sugar (for filling)
• 3 tablespoons low or no-sugar-needed fruit pectin
• Pinch salt (for filling)
• 10 ounces (2 cups) fresh or thawed frozen blueberries

Directions

1. Preheat oven to 325 degrees. Heavily spray a 12 cup nonstick Bundt pan with baking spray and dust with flour.
2. Whisk flour, baking powder, baking soda, salt, and cinnamon together in a large bowl.
3. Whisk buttermilk, lemon zest and juice, and vanilla together in a medium bowl.
4. Gently whisk eggs and yolk to combine in a third bowl.
5. Using a mixer with the paddle attachment, beat butter and sugar on medium-high speed until pale and fluffy, about 3 minutes, scraping down the bowl as needed. Reduce speed to medium and beat in half of the eggs until incorporated, about 15 seconds. Repeat using half of the remaining flour mixture and all of the remaining buttermilk mixture. Scrape down bowl, add remaining flour mixture and mix at medium-low speed until batter is thoroughly combined, about 15 seconds. Remove bowl from mixer and fold batter once or twice with a rubber spatula to incorporate any remaining flour. Cover bowl with plastic wrap and set aside while preparing the filling.
6. For the filling: whisk sugar, pectin and salt together in a small saucepan. Process blueberries in a blender until mostly smooth, about 1 minute. Transfer ¼ cup puree and the lemon zest to the saucepan with the sugar mixture and stir to thoroughly combine. Heat the sugar-blueberry mixture over medium heat until just simmering, stirring frequently to dissolve the sugar and pectin. Transfer mixture to a medium bowl and let cool for 5 minutes. Add remaining puree and lemon juice to the cooled mixture and whisk to combine. Let sit until slightly set, about 8 minutes.
7. Spoon half of the batter into the prepared pan and smooth the top. Using the back of a spoon, create a 12 inch deep channel in the center of the batter. Spoon half of the filling into the channel. Using a butter knife or small offset spatula, thoroughly swirl the filling into the batter (there should be no large pockets of filling remaining). Repeat the swirling step with the remaining batter and filling.
8. Bake until the top is golden brown and a skewer inserted in the center comes out with no crumbs attached, 60-70 minutes.
9. Let cake cool in pan on a wire rack for 10 minutes, then invert cake directly onto the wire rack; let cake cool for at least 3 hours before serving.