01 - Preheat oven to 400°F. Line a baking sheet with parchment paper and set aside.
02 - In a large bowl, whisk together the flour, sugar, baking powder, and salt until evenly combined.
03 - Add the cubed cold butter to the flour mixture. Using your fingers or a pastry blender, cut the butter into the dry ingredients until the mixture resembles coarse crumbs with pea-sized pieces remaining.
04 - In a small bowl, whisk together the heavy cream and egg. Pour the wet mixture into the dry ingredients and stir gently with a fork just until the dough comes together. Do not overmix.
05 - Turn the dough out onto a lightly floured surface. Gently pat it into a ¾-inch thick round. Cut into small squares or rounds, approximately 1 inch in size, suitable for layering in individual trifle glasses.
06 - Arrange the shortcake pieces on the prepared baking sheet. Bake for 12 to 15 minutes, until the tops are golden brown and a toothpick inserted in the center comes out clean. Transfer to a wire rack and cool completely.
07 - Place the sliced strawberries in a medium bowl. Add the granulated sugar and lemon juice, tossing gently to coat. Let stand at room temperature for at least 15 minutes until the berries release their natural juices and form a light syrup.
08 - In a chilled mixing bowl, combine the cold heavy cream, powdered sugar, and vanilla extract. Beat on high speed with an electric mixer until stiff peaks form, being careful not to overwhip.
09 - In each serving glass, create layers starting with shortcake pieces at the bottom, followed by a generous spoonful of macerated strawberries and their juices, then a dollop of whipped cream. Repeat the layers once more. Finish each trifle with a final swirl of whipped cream and garnish with a few fresh strawberry slices.
10 - Serve the trifles immediately, or cover and refrigerate for up to 2 hours before serving to allow the flavors to meld.