Crumble the sausage into a large skillet set over medium-high heat. Cook, stirring occasionally, for 8-10 minutes, or until browned and cooked through. Transfer the sausage to a plate and discard any grease that has accumulated in the bottom of the pan.
Return the pan to the stove and add the onion; cook 1 minute. Add the sweet potato and mined jalapeño; cook 3 minutes. Pour in the beer. Bring to a simmer and cook 10 minutes, or until the sweet potato is soft and the liquid has evaporated. Stir in the cooked sausage, chili powder, and scallions.
Place a tortilla on a flat work surface. Scatter 1/8 of the cheese over half the tortilla. Spread 3/4-cup of the sausage filling over the cheese. Add a few jalapeño slices, if desired. Top with more cheese. Fold the tortilla in half. Repeat with remaining tortillas to make 4 quesadillas.
Heat 1 tablespoon of oil on a griddle (or in a large pan) set over medium-high heat. Cook the quesadillas one at a time, for 1-2 minutes per side, or until the tortilla is golden brown and the cheese is melted.
Cut each quesadilla into 4 wedges. Serve with salsa, sour cream, and guacamole for dipping.