Using a fork or a dough mixer, blend the contents of the Chebe mix packet in a bowl with 2 Tbsp oil or softened butter and 2 eggs. Add 5 Tbsp of milk, milk substitute, or water while continuing to mix. Knead dough with hands until all ingredients are fully blended and the dough is smooth. Roll dough into a ball. Using a rolling pin, roll dough into a thickness of 1/4 inch or less. Using a knife or pastry scraper, cut into 5 x 7 inch rectangles. (Scraps of remaining dough can be kneaded together and re-rolled to create additional rectangles.)
In a frying pan over low heat, add butter, oil and onion. Cover and cook 10-15 minutes or until soft, then remove cover and cook until the onions begin to turn golden brown. Remove from heat. Add onions to mashed potato/spinach combination, as well as pepper and 1/2 tsp of kosher salt. Stir in one egg. Use wooden spoon or masher to combine.
Using a pastry scraper, carefully transfer each rectangle of dough to the greased baking sheet. Place a small amount of the mashed potato mixture (approximately 2-3 Tbsp.) in the center of each rectangle, arranging it so that there is at least a 1 1/2 inch perimeter of dough around the filling on all sides. Make absolutely sure that no filling or liquid gets on the perimeter of the dough, as it will keep the knish from sealing. Fold dough over widthwise (shorter side to shorter side). Use a fork to crimp the edges of the dough. Make sure all the edges are sealed, and patch any holes with small scraps of dough.
Brush the 3 Tbsp of oil or egg you have set aside over the top of each knish. Bake for 20-25 minutes, or until golden. Eat while hot or warm. Refrigerate or freeze leftovers and reheat in the oven (without defrosting).
Recipe and photos by Gluten-Free Bay
Chēbē baking mixes, with the exception of Original Chēbē Cheese Bread Mix, are certified OU Kosher.