Preheat your oven to 420°F (400°F for fan ovens) and line a baking sheet with parchment paper. Hull and chop the strawberries into 1/2-inch pieces, then spread them on a plate and freeze for 30-60 minutes—this keeps them from melting into the dough and creates little bursts of fruit throughout. While strawberries freeze, cube the cold butter into 1/2-inch pieces and keep it cold in the fridge. Make sure your mashed potato is cooled and smooth before you start mixing the dough.

In a large bowl, whisk together the flour, sugar, baking powder, and salt. This combines all your dry ingredients evenly and incorporates air into the flour, which helps create a light, fluffy scone texture.

Add the cold cubed butter to the dry mixture and use your fingertips or a pastry cutter to rub the butter into the flour until the mixture resembles coarse breadcrumbs—this creates little pockets of butter that steam during baking, making the scones tender and flaky. Add the cooled mashed potato and gently fold it in with a spatula until the mixture comes together. I find that folding rather than stirring helps keep the dough light and prevents overworking it.

In a small bowl, whisk together 1 egg and 4 tbsp milk. Pour this mixture into the dry ingredients and stir gently with a spatula just until a shaggy dough forms—do not overmix, as this develops gluten and makes scones tough. The dough should look a bit rough and underdeveloped at this stage, which is exactly what you want.

Flour a work surface lightly and turn the dough out onto it. Roll or gently press the dough to about 4cm (1.5 inches) thick. Scatter half of the frozen strawberries evenly over the dough, then fold the dough in half over itself and gently press down. Roll the dough out again to 4cm thick, scatter the remaining frozen strawberries on top, fold it in half again, and press gently. This folding technique, called lamination, creates layers in the dough while distributing the strawberries throughout. Roll the dough one final time to about 5cm (2 inches) thick.

Using a 2-3 inch round cutter (or a drinking glass), cut 6 scones from the rolled dough and place them on your prepared baking sheet, spacing them about 2 inches apart. In a small bowl, whisk together the remaining egg and 1 tbsp milk to create an egg wash, then brush the mixture generously over the top of each scone. This creates a beautiful golden-brown exterior during baking.

Bake the scones at 420°F for 20 minutes, rotating the baking sheet halfway through (around the 10-minute mark) to ensure even browning. The scones are done when the tops are golden brown and a toothpick inserted into the center comes out clean. I like to let them cool for 2-3 minutes on the baking sheet before transferring to a wire rack—this helps them set without becoming hard.