Mix the sugar and the butter in a bowl and heat it in the microwave for 1 minute until the butter melts. Spread the mixture of butter and sugar over the tortillas on both sides with a pastry brush.
Now you have several options to shape the tortillas into taco shells. My favorite is to take a donut mold or cupcake mold, turn it around, place the tortillas in the gaps between the donuts, and heat it in the oven for 10 to 15 minutes over 350 F (180º C).
Meanwhile, your tacos are in the oven. You can start whipping the cream or, if you prefer, you can use store-bought whipped cream saving some effort and time.