- Heat oil to 190ºC (375ºF).
- In a medium saucepan, combine milk, water, butter until just starting to melt. Add sugar and stir to dissolve and bring to a simmer.
- Add flour all at once. Stir until the dough pulls away from the sides of the pan and forms a ball. Remove from heat and let cool for 4 minutes.
- Stir in eggs one at a time until fully combined.
- Using a small star-tip in a piping bag, pipe about 3-4-inch long churros. Fry until golden brown.
- Mix 1 cup sugar and cinnamon together. Toss churros in sugar mixture. Sprinkle chocolate evenly over top and top with marshmallows. GRill in the oven for 5 minutes until chocolate is melted and marshmallows are toasted and melted.