In a large bowl, combine flour, baking powder, rosemary, and salt. Using a pastry blender, cut butter into flour mixture until mixture resembles coarse crumbs. Add cheese, tossing to combine.
In a liquid-measuring cup, combine cream and egg, whisking well. Gradually add to flour mixture, stirring until mixture is evenly moist. (If mixture seems dry, add more cream, 1 tablespoon at a time.) Working gently, bring mixture together with hands until a dough forms.
Turn out dough onto a lightly floured surface, and roll to a ½-inch thickness. Using a 3-inch round cutter, cut 12 scones, rerolling scraps as needed. Place scones 2 inches apart on prepared baking sheet.
Brush scones with olive oil, and sprinkle with sea salt.
Bake until scones are lightly lightly browned, 11 to 13 minutes.
Garnish with rosemary sprigs, if desired.
Recipe by TeaTime Magazine at https://teatimemagazine.com/rosemary-white-cheddar-scones-recipe/