In a medium bowl, combine the diced strawberries, 2 tablespoons of granulated sugar, and lemon juice. Stir gently and let sit at room temperature for at least 15-20 minutes, stirring occasionally, while you prepare the shortbread. This allows the strawberries to release their juices and create a delicious syrup.

Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

In a large mixing bowl, whisk together the flour, 1/2 cup granulated sugar, baking powder, and salt.

Add the cold, cubed butter to the dry ingredients. Using a pastry blender, your fingertips, or a food processor, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining.

In a small bowl, combine the milk and 1 teaspoon vanilla extract. Pour the wet ingredients into the dry ingredients and mix with a rubber spatula or your hands until just combined and a soft dough forms. Be careful not to overmix.

Turn the dough out onto a lightly floured surface. Gently pat or roll the dough to about 1/2-inch thickness. Using a 2.5-inch round cookie cutter (or the rim of a glass), cut out shortbread rounds. You should get about 12 cookies. Reroll scraps gently as needed.

Place the shortbread rounds on the prepared baking sheet. Sprinkle the tops evenly with the remaining 2 tablespoons of granulated sugar.

Bake for 12-15 minutes, or until the edges are lightly golden brown. The centers should still be pale. Let cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

While the shortbread cookies are cooling, in a chilled large mixing bowl (or the bowl of a stand mixer), combine the cold heavy cream, powdered sugar, and 1/2 teaspoon vanilla extract.

Using an electric mixer with a whisk attachment, beat on medium-high speed until stiff peaks form, about 2-4 minutes. Be careful not to overbeat, or it will turn to butter.

Once the shortbread cookies are completely cool, gently spread a generous dollop of vanilla whipped cream on the bottom of one cookie.

Spoon a tablespoon or two of the macerated strawberries (including some of the syrup) over the whipped cream.

Top with another shortbread cookie, pressing down gently to form a sandwich. Repeat with the remaining cookies, whipped cream, and strawberries.

Serve immediately for the best texture, or chill briefly until ready to serve.