01 - Preheat the oven to 400°F. Line a muffin tin with paper liners or lightly grease the cups with butter or cooking spray.
02 - In a large mixing bowl, whisk together the all-purpose flour, 1/4 cup granulated sugar, baking powder, and salt until well combined.
03 - Add the cold cubed butter to the flour mixture. Use a pastry cutter or clean fingertips to work the butter into the dry ingredients until the texture resembles coarse crumbs with some pea-sized pieces remaining.
04 - In a small bowl, whisk together the whole milk, beaten egg, and 1 teaspoon vanilla extract until fully incorporated.
05 - Pour the wet mixture into the flour and butter mixture. Stir gently with a spatula or wooden spoon just until the dough comes together. Be careful not to overmix, which can make the shortcake tough.
06 - Divide the dough evenly among the 6 prepared muffin cups. Bake for 16 to 18 minutes until the tops are lightly golden and a toothpick inserted into the center comes out clean. Allow to cool completely in the pan before removing.
07 - While the shortcakes bake, combine the sliced strawberries with 1/4 cup granulated sugar and lemon juice in a medium bowl. Toss gently to coat. Let stand at room temperature for at least 15 minutes, stirring occasionally, until the strawberries release their juices and become syrupy.
08 - Place the chilled heavy whipping cream in a clean, cold bowl. Add the powdered sugar and 1/2 teaspoon vanilla extract. Beat with an electric mixer on medium-high speed until soft peaks form when the beaters are lifted. Do not overbeat or the cream may separate.
09 - Slice each cooled shortcake horizontally in half. Place the bottom half in a serving dish or cup. Spoon some macerated strawberries over the base, then top with a generous dollop of whipped cream. Cover with the top half of the shortcake and add another layer of strawberries and whipped cream. Serve immediately while the shortcakes are fresh.