Preheat oven to 300°F (150°C). Place a heatproof wire rack directly on oven rack, creating a sturdy, metal, cross-hatched surface to help keep pan level.

In a large bowl, whisk together melted butter, sugar, ½ cup (170 grams) honey, goat’s milk or buttermilk, eggs, egg yolk, and lemon zest and juice.

In a medium bowl, whisk together cornmeal, 1½ cups (188 grams) flour, salt, baking powder, and baking soda. Gradually whisk flour mixture into butter mixture just until some bits of flour remain.

In a small bowl, toss together blackberries and remaining 1 tablespoon (8 grams) flour. Fold blackberry mixture into batter just until combined.

Spray a 10-cup Bundt pan with baking spray with flour. Using a ¼-cup spring-loaded scoop, scoop batter into prepared pan. Forcefully tap pan on a kitchen towel-lined counter several times to settle batter and release any air bubbles.

Bake for 40 minutes. Rotate pan, and loosely cover with foil to prevent excess browning, if necessary; bake until a wooden pick inserted near center comes out clean and an instant-read thermometer inserted near center registers 200°F (93°C), 30 to 40 minutes more. Let cool in pan for 10 minutes. Invert cake onto a wire rack placed over a rimmed baking sheet.

In a small microwave-safe bowl, heat remaining 2 tablespoons (42 grams) honey on high in 10-second intervals, stirring between each, until loose and fluid. Quickly and carefully brush onto warm cake. Let cool completely.

Transfer cooled cake to a serving plate. Garnish with honey, if desired.