Sift together the Cup4Cup gluten-free flour and cornstarch (if using) in a medium bowl.

In a medium saucepan, combine 1 cup of water, 1/2 cup of butter, 1 tablespoon of sugar, and 1/4 teaspoon of salt.

Once simmering, add the dry ingredients and stir vigorously until the dough forms and pulls away from the sides of the pan.

Return the pan to low heat and stir for an additional minute to slightly dry out the dough.

Transfer the dough to a food processor and let it cool for about 5 minutes, then pulse briefly.

With the food processor running, gradually add 3-4 room-temperature eggs until fully incorporated.

Transfer the dough into a piping bag fitted with a star tip and chill for 15-30 minutes.

In a shallow dish, combine 1 cup of granulated sugar with 1 tablespoon of ground cinnamon.

Heat vegetable oil in a deep skillet to 360°F using a kitchen thermometer to maintain accuracy.

Pipe 4-6 inch strips of dough into the hot oil and fry for 90 seconds to 2 minutes per side.

Once golden, drain the churros on a plate lined with paper towels and roll in the cinnamon-sugar mixture.