Preheat oven to 425 degrees and grease a baking sheet with butter.
In a large bowl, whisk together flour, baking powder, sugar, salt, and chili powder.
Scatter butter cubes across flour mixture and use a pastry cutter or your fingers to cut the butter in until there are no pieces larger than a small pea.
Stir in sweet potato and cheese.
Add 3/4 cup milk and stir just until flour is moistened. If it is not coming together into a dough, add a little more milk.
Place dough on a lightly floured surface and roll or pat out to 1-inch thickness. Cut into biscuits with a 2 1/2-inch biscuit cutter. Gather scraps and roll to cut more biscuits. You should get at least 8 biscuits.
Place biscuits on prepared baking sheet and bake for 12 to 15 minutes.
To make gravy, brown chorizo in a nonstick pan, breaking it apart with a wooden spoon as it cooks. Once cooked all the way, remove chorizo from pan with a slotted spoon and set aside.
Leave grease in pan and add butter to it. Heat over medium heat. When butter has melted, add flour. Stir and cook for 1 minute.
Gradually whisk in milk. Add pepper and cook until thickened.
Return chorizo to pan. Stir to mix and keep warm until ready to eat.