2) For the quesadillas; heat a large nonstick frying pan or griddle over a medium-high heat. Spread 1 side of each tortilla with butter.
3) Lay 2 tortillas in the pan, buttered side down, and scatter half the chocolate randomly over each.
4) Sprinkle each with 1 tsp cocoa chili powder and cover with the remaining tortillas, buttered side up. Cook until the chocolate starts to melt, about 3 to 4 minutes.
5) Carefully flip over and cook the other side until evenly browned, an additional 3 to 4 minutes. Remove from the heat to a cutting board, leave to rest for 3 to 4 minutes, then cut each into 4 quarters.
6) To plate, put 1 scoop of ice cream into each serving dish, add 2 pieces of quesadilla and drizzle with the dark chocolate sauce. Dust each dish evenly with the remaining tsp of the cocoa chili powder. Serve immediately.