1. Preheat the oven to 375F. Line 2 baking sheets with parchment paper.

2. In a small bowl, whisk together the eggs, sour cream and 2 tablespoons of the mustard. Set aside.

3. In a large bowl, whisk together the flour, salt, sugar and baking powder. Add the butter pieces. Use your fingers to rub the butter into the flour until the mixture looks crumbly and there are no visible bits of butter.

4. Add the sour cream mixture to the flour-butter mixture. Stir with a spoon to just roughly combine; add the grated Gruyere cheese. Now use your hands to form a dough, gently pressing and pushing the mixture together. Turn the dough out onto a floured board or counter. Press the dough into a 12-x-5-inch rectangle. Use a sharp knife or pastry cutter and cut the dough in half lengthwise so each piece is about 12x2 1/2 inches. Cut each strip into 6 equal pieces, then cut each piece in half diagonally to form triangle-shaped scones. Transfer the scones to the prepared baking sheets. Brush the tops with the remaining tablespoon of mustard.

5. Bake 15 to 20 minutes or until lightly browned and cooked through.

This recipe is adapted from The King Arthur Flour Baker's Companion