Preheat the oven to 400°F (207°C). Line a baking sheet with parchment paper.
Combine the flour, 3 tablespoons sugar, baking powder and salt into a bowl. Add the cold butter and use your fingertips to pinch and rub until the butter is well incorporated. The mixture will resemble a coarse meal.
Use a wooden spatula to combine the beaten egg and heavy cream into the dry ingredients until it forms a soft dough. Then stir in the strawberries.
Lightly floured the working surface, use your hand and knead the dough until it comes together. Make the dough into a ball. Let it rest uncovered for 2-3 minutes.
Dust more flour on top (if the dough is too wet) and pat it into a 9-inch round disc, about 1/2 inch thick.
Using a floured knife, cut the dough into 8 wedges and arrange them 1 inch apart on the baking sheet.
For the glaze, brush the scones with the heavy whipping cream and sprinkle with the sugar.
Bake the scones for 18-20 minutes, until the bottom is lightly browned. Remove from oven and let them rest on the baking sheets for 3-5 minutes.
Serve warm with butter and strawberry jam.
Notes
Alternately, you can roll the dough into a 10 by 12 inches rectangle and cut into 8 triangular scones.