01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together the flour, sugar, baking powder, and salt. Add the cubed cold butter and cut it in using your fingers or a pastry blender until the mixture resembles coarse crumbs with pea-sized pieces.
03 - In a small bowl, whisk the heavy cream and egg together. Pour into the dry mixture and stir gently just until a soft dough comes together. Do not overmix.
04 - Turn the dough out onto a lightly floured surface and gently pat it into a ¾-inch thick round. Cut into small 1-inch squares or rounds suitable for layering in individual glasses.
05 - Arrange the shortcake pieces on the prepared baking sheet. Bake for 12 to 15 minutes until golden brown on top. Transfer to a wire rack and let cool completely.
06 - Place the sliced strawberries in a bowl and toss with granulated sugar and lemon juice. Let stand at room temperature for 15 minutes until the berries release their natural juices.
07 - In a chilled mixing bowl, beat the cold heavy cream, powdered sugar, and vanilla extract on high speed using an electric mixer until stiff peaks form. Be careful not to overwhip.
08 - Layer shortcake pieces, macerated strawberries with their juices, and whipped cream in individual serving glasses. Repeat the layers once more. Finish each glass with a dollop of whipped cream and a few fresh strawberry slices on top.
09 - Serve immediately, or cover and refrigerate for up to 2 hours before serving to allow the flavors to meld.