My mother made this EVERY Thanksgiving of my life and it is a staple on my table every year. I rarely make it at other times, although I would certainly like it. Kids aren't generally a fan but all my adult children and family love this.
1Cook peas as directed until about 2/3 done. Drain and return to pot. Set aside.
Melt 3 tblsp butter in sauce pan, add flour and let cook on medium heat just until it starts to get color. Add salt and pepper. Add milk and juice from jar of onions. Cook until thickens!
2Add onions to cream mixture, turn to low and let heat through. Don't mix too much as you want onions to retain shape. Stir cream sauce into peas.
3Pour into buttered baking dish and cover. Bake, at 350 degrees for 25 minutes. Uncover and bake for 15 more minutes, until bubbling around the edges.
NOTE:: you can make it all ahead except for baking, store in fridge for a day and put in oven from the fridge adding 15 minutes to covered cooking time.