Preheat oven to 400° and line a baking sheet with parchment paper. In a medium bowl, whisk together 1 cup cream and egg. In a large bowl, whisk together flour, sugar, baking powder, and salt.
Using your fingers, rub butter into flour mixture until it resembles coarse meal, with a few pea-size pieces of butter remaining. Add ¾ cup of cheddar, Gruyère, and green onions, and toss to coat.
With a fork, stir in cream mixture until just combined. (The dough should be crumbly; do not overwork.)
Transfer dough to a work surface and pat into a 6" circle and cut into 6 wedges. Arrange scones on prepared baking sheet. Brush tops with remaining 1 tablespoon cream and sprinkle with remaining ¼ cup of cheddar cheese.
Bake until golden, 18 to 20 minutes, rotating sheet halfway through.
Recipe by The Best Video Recipes for All at https://recipes-for-all.com/extra-cheesy-scones/