Preheat oven to 400 degrees F.
While dough is in the refrigerator, prepare the filling. Arrange the delicata squash slices on a large baking sheet. Drizzle with 2 tbsp olive oil and salt. Roast for 30 minutes.
While squash is roasting, heat 1 tbsp olive oil in a skillet over low heat. Add onion slices and cook until caramelized, stirring occasionally. This should take about 25 minutes.
Once squash is roasted and onions are caramelized, add them to a large bowl. Gently mix in halloumi, honey, cayenne, salt, pepper.
Remove the dough from the fridge. Roll dough on a floured surface, into a circular shape about ¼-in thick (this doesn't have to be perfect, sine galettes have a "rustic" shape).
Place the dough on a parchment lined baking sheet. Add the filling in the center, leaving a 2-inch border of crust. Once all of the filling is added into the center, fold the crust over the top of the filling.
Brush the crust with the egg wash. Sprinkle with pine nuts, grated halloumi, and dried mint.
Bake the galette until the crust is golden, about 40-50 minutes. Removed from the oven and let cool slightly. Sprinkle with pomegranate arils before serving.