Preheat and Prep: Preheat oven to 400F (200C). Line a baking sheet with parchment paper.
Dry Ingredients: In a large bowl, whisk together the gluten-free flour blend, sugar, baking powder, baking soda, and salt.
Cut in Butter: Cut in the cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs.
Wet Ingredients: In a separate bowl, combine the buttermilk and vanilla extract.
Combine Wet and Dry: Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Do not overmix.
Drop Biscuits: Drop spoonfuls of dough (about cup each) onto the prepared baking sheet.
Bake: Bake for 20-25 minutes, or until golden brown. Let cool on a wire rack.
Prepare Strawberries: In a bowl, combine the sliced strawberries, sugar, and lemon juice (if using). Gently toss and let sit for at least 15 minutes to macerate.
Make Whipped Cream: In a chilled bowl, whip the heavy cream with powdered sugar and vanilla extract until stiff peaks form.
Assemble Shortcakes: Split the cooled shortcakes in half. Spoon the macerated strawberries over the bottom halves, top with whipped cream, and place the top halves of the shortcakes on top. Serve immediately.
Tips and Substitutions: For a dairy-free option, substitute the buttermilk with a non-dairy milk alternative and use a plant-based butter substitute. Coconut whipped cream can replace traditional whipped cream. The granulated sugar can be substituted with maple syrup. Ensure the gluten-free flour blend contains xanthan gum, or add it separately (about teaspoon per cup of flour blend).