Preheat the oven to 425°F (220°C). Line a baking sheet with parchment paper and set aside.

In a large mixing bowl, whisk together the flour, baking powder, granulated sugar, lemon zest, and salt. Incorporate the grated cold butter into the dry ingredients using a pastry cutter or your fingertips until the texture resembles coarse crumbs.

Gradually pour in the buttermilk and mix gently with a wooden spoon until a shaggy dough forms. Avoid over-mixing to ensure tender biscuits.

Transfer the dough to a floured surface. Roll it into a rectangle, fold it into thirds (like a letter), then repeat the rolling and folding once more. Wrap the dough in plastic wrap and allow it to rest in the refrigerator for 30 minutes.

After resting, roll the dough to about ¾ inch thickness and cut into 6 to 8 portions. Arrange them close together on the prepared baking sheet. Brush the tops with the egg wash and sprinkle with raw sugar. Bake for 12 to 15 minutes or until golden brown. Cool on a wire rack.

In a mixing bowl, combine the sliced strawberries, sugar, and lemon juice. Gently stir to coat. Allow the mixture to sit at room temperature for at least 20 minutes to release juices.

In a stand mixer fitted with a whisk attachment (or using a hand mixer), combine mascarpone cheese, heavy cream, maple syrup, vanilla extract, and salt. Beat until soft peaks form. Chill until ready to use.

Slice the cooled biscuits in half horizontally. Spoon a generous layer of whipped cream onto the bottom half, followed by a portion of macerated strawberries. Place the top half of the biscuit over the filling. Optionally, top with additional cream and strawberries before serving.