Heat half the olive oil in a pan over medium heat, add onion, peppers and mushrooms, cook until tender then remove from pan.
Add 2 more tablespoons olive oil to pan and stir in sweet rice flour, whisking until smooth. While continuing to whisk, gradually add broth, cooking until sauce thickens. Stir in mayonnaise, parsley, thyme, salt and pepper, whisking until smooth. Turn off heat.
Mix in onion/pepper/mushroom mixture, artichoke hearts, peas and tuna. Spread cooked pasta in 4 8×8 lightly oiled baking dishes and pour tuna mixture over noodle being sure to cover the noodles completely.
If using a topping, sprinkle gluten free bread crumbs over the casserole, dust lightly with paprika. Spritz bread crumbs with a bit of olive oil. If using potato chips, simply sprinkle crushed potato chips over all. If not using a topping, lightly dust with paprika. Cover, label and freeze.
If serving one right away, bake in the preheated 350 degree oven for 30 minutes until lightly browned on top.
Bake from Frozen: Preheat oven to 350 degrees. Bake, covered with foil, until center is warm, about 2 hours. Uncover, and bake until top is browned, about 20 minutes more.
Bake from Thawed: Thaw overnight in refrigerator. Preheat oven to 350 degrees and bake, covered with foil, until center is warm, about 30 minutes. Uncover, and bake until top is browned, about 20 minutes more.