Cut butter into ¼-inch pieces and return it to the refrigerator to keep it cold until needed.
Preheat oven to 425° F. Line a baking sheet with parchment paper.
Combine flour, sugar, baking powder, salt, and lemon zest in a large wide bowl. Mix to combine.
Add butter to the dry ingredients and toss it to coat with flour. Working quickly with clean fingers or a pastry blender, rub or cut butter into the flour mixture until it resembles coarse meal.
Add frozen raspberries to the mixture and toss to coat. Drizzle the heavy cream evenly over the mixture. Toss with a fork, scraping up from the bottom, until the dough starts to clump together. Knead the mixture together in the bowl until it comes together in a mass. It's okay if there are a few crumbs and stray bits.
Turn out the dough on a parchment-lined baking sheet. Press in stray bits gently and shape the dough into an a 7 to 8-inch square about 3/4-inch thick.
Using a knife or bench scraper, divide the square into 9 smaller squares. Divide each square in half diagonally to make 18 small triangles.
Separate the scones carefully to give them room to spread. Bake until pale golden, about 12 to 15 minutes.
To prepare the glaze, combine lemon juice and 1/2 cup confectioners’ sugar in a small bowl. Whisk to combine. Add more sugar, as needed to create the desired consistency for glazing.
Cool scones for at least 10 minutes before glazing. Serve warm or at room temperature.