Step 1

Place 3 cups of the all-purpose flour, 1/4 cup of the granulated sugar, 1 tablespoon plus 1 1/2 teaspoons baking powder, 1 1/4 teaspoons kosher salt, and 3/4 teaspoon ground cinnamon in a large bowl and whisk to combine.

Step 2

Grate 1 1/2 sticks cold unsalted butter on the large holes of a box grater directly into the flour. Toss the butter into flour with a flexible spatula, breaking up any large clumps of butter. While stirring constantly, gradually pour in 2 1/4 cups of the cold heavy cream. Continue stirring and gently pressing to combine, until the mixture is mostly combined and barely any dry spots remain. Fold together, scraping the sides and bottom of the bowl, until a shaggy, sticky dough forms.

Step 3

Transfer the dough onto a floured work surface. Fold the dough over itself a few times until it comes together. Pat into a rough 12x10-inch rectangle about 1/3-inch. Use a 2-inch diameter cookie or biscuit cutter to punch out rounds. Gather any scraps and repeat as needed until you have 30 rounds. (Alternatively, cut the dough into 30 (2-inch) squares.)

Step 4

Line 2 rimmed baking sheets with parchment paper. Transfer the biscuits to one of the baking sheets. Refrigerate for at least 15 or up to 30 minutes. Meanwhile, arrange 2 racks to divide the oven into thirds and heat the oven to 375°F.

Step 5

Transfer half of the biscuits to the second baking sheet and space all the biscuits apart evenly. Bake 15 minutes. Rotate the baking sheets from top to bottom and from front to back. Continue baking until puffed and golden-brown, 10 to 17 minutes more. Let cool completely on the baking sheets.

Step 6

Meanwhile, place 2 pounds frozen mixed berries, 3/4 cup of the granulated sugar, and the remaining 1 1/2 tablespoons all-purpose flour in a large saucepan and stir to combine. Cover and cook over medium-low heat, stirring often, until the mixture is syrupy, thickened, and the berries break down but still maintain their shape, 6 to 8 minutes. Uncover and let cool completely, about 45 minutes.

Step 7

Place 16 ounces cold mascarpone cheese, 1 1/2 teaspoons vanilla extract, remaining 2 1/4 cups cold heavy cream, and remaining 2 tablespoons granulated sugar in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Beat with the whisk attachment on medium speed until medium peaks form, 2 to 4 minutes. Refrigerate until ready to assemble.

Step 8

Trim 1 pound fresh strawberries and halve or quarter if large (about 3 cups). Place in a medium bowl, add 10 ounces fresh blueberries (1 pint), and gently toss to combine.

Step 9

Assemble the trifle: Reserve 1/3 cup of the syrupy berries for drizzling. Reserve 3 biscuits for the top. Quarter the remaining biscuits.

Step 10

Place 1/3 of the quartered biscuits (27 pieces) in the bottom of a 3.6-quart or larger trifle bowl or large glass bowl, pressing them down into a tight layer and some against the sides. Spoon about 1 1/3 cups of the syrupy berries evenly over the biscuits. Top with 2 generous cups of the mascarpone cream and spread into an even layer (it’s okay if a swirling effect happens with the syrupy berries and the mascarpone cream). Sprinkle with 1 1/2 cups of the fresh berries.

Step 11

Repeat layering the biscuits, syrupy berries, mascarpone cream, and fresh berries two more times. Quarter 1 1/2 of the remaining biscuits and crumble the rest. Stand the quartered pieces straight up in the top and sprinkle with the crumbs. Drizzle with the reserved syrupy berries. Scoop to serve.