Cover a baking sheet with a piece of parchment paper, and set aside.
Place the cheddar cheese and chiles in a small bowl, and toss to combine; set mixture aside.
In a small bowl, lightly beat 3 eggs and the cream, and set aside.
Using an electric mixer fitted with the paddle attachment, combine flour, baking powder, chile powder, and salt. Add butter; mix on low speed until the butter is in pea-size pieces, 1 to 2 minutes. Add egg and cream mixture; mix on low speed until just blended. Add cheese and chile mixture; mix until just combined.
Transfer dough to a well-floured surface, and pat into a 9-inch circle. Using a sharp knife dipped in flour, cut circle into 8 to 12 wedges. Transfer wedges with a spatula to prepared baking sheet; brush tops with egg wash.
Place in oven; bake, until outside is crusty and inside is cooked through, 15 to 20 minutes. Transfer to a wire rack to cool.
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Notes
Green chile: Fresh roasted Hatch green chile is ideal, but canned chopped green chiles work great too. Be sure to drain well before adding.
Cheese options: Sharp cheddar gives these scones a bold flavor, but feel free to try pepper jack, Monterey Jack, or a Mexican cheese blend.
Make-ahead: Shape the scones and freeze before baking. When ready to bake, add a few extra minutes to the oven time.
Serving suggestions: Delicious warm with butter or paired with pozole, huevos a la mexicana, Mexican chili beans, or chile verde con carne y papas.
Storage: Store in an airtight container at room temp for 2 days, or in the fridge for up to 5 days. Freeze for up to 3 months.