Position rack in center of oven and preheat to 375°F.
Heat oil in large skillet over medium heat. Add onion; sauté until golden. Season with salt and pepper.
Mix flour, baking powder, and salt in large bowl. Mix in cheese. Stir in onion mixture. Gradually add cream, stirring until dough comes together. Knead gently in bowl 5 turns. Turn dough out onto lightly floured work surface. Divide dough in half; sprinkle lightly with flour if sticky. Pat each half into 3/4-inch-thick round. Cut each round into 6 wedges.
Transfer wedges to large baking sheet, spacing evenly apart. Bake scones until tops are golden brown and tester inserted into center comes out clean, about 20 minutes.
Transfer scones to rack and cool slightly. Serve warm or at room temperature.