Step 1

Preheat the oven to 400°F with a rack in the center.

Step 2

, To prepare the fruit: In a medium bowl, toss together the berries, sugar, zest, and lemon juice. Let sit until the fruit is glossy and has started to release its juice, at least 30 minutes and up to 4 hours.

Step 3

, To make the batter: In a large bowl, whisk together the sugar, flours, baking powder, and salt.

Step 4

, In a small bowl or liquid measuring cup, whisk together the milk, egg, and vanilla.

Step 5

, Place the butter in an 8” square pan or 1 1/2- or 2-qt. baking dish and put it in the oven to melt; it’ll take 4 to 6 minutes using butter that’s cold from the fridge.

Step 6

, Once the butter has melted, swirl it around in the baking dish so it coats the sides, then pour it into the flour mixture and stir with a spatula to thoroughly combine.

Step 7

, Add the milk mixture and whisk well to incorporate.

Step 8

, Immediately transfer the batter to the warm buttered baking dish, then gently spoon the macerated fruit and its juice over the top. The fruit mixture should cover the batter almost entirely with a few bare spots peeking through.

Step 9

, To bake the cake: Bake until golden brown and puffed, 30 to 35 minutes.

Step 10

, Remove from the oven and serve warm. Whipped cream or ice cream dolloped on top is especially delicious.

Step 11

, Storage information: Refrigerate any leftovers, covered, for up to four days.