In a large bowl, add in the roasted acorn squash. Mash the squash with a fork to desired consistency – I like mine almost smooth but with a few small chunks.
Add in the egg, salt, pepper, and baking powder. Stir to combine. Add in the flour and combine gently until batter just comes together. Pop the bowl into the fridge as the oil comes to temperature.
In a skillet with high sides set over medium heat, pour in just enough vegetable oil to barely coat the surface. When the oil starts to glisten, portion out heaping tablespoons of batter into the skillet to form the fritters. Cook the fritters for 1-2 minutes per side or until golden brown. Carefully flip the fritters over and cook for an additional 1-2 minutes. A word of warning… THIS IS HOT OIL, SO PLEASE, PLEASE BE CAREFUL. If you have small kids or pets running around, I would wait to fry these up until the kiddos are safely away from the stove.
Remove the cooked fritters from the oil onto a paper towel-lined plate to drain off any excess grease. Finish cooking the remaining fritters.
To make the sauce – combine all sauce ingredients in a small bowl. Mix to combine.