Place all vegetables on a large baking sheet that has been sprayed with non-stick spray. Drizzle with extra virgin olive oil or melted coconut oil and a few shakes of salt. Roast in the heated oven for about 30-40 minutes, tossing every 10-15 minutes so nothing sticks to the pan.
When there are about 5 minutes left on the vegetables, butter 4 slices of bread, on one side only. Place butter side down in a skillet on medium heat. Let heat long enough to get golden brown bread on the one side. The edges will start to get crispy.
Turn on your broiler and place your slices of bread, butter side down again, on a baking sheet. Place a slice of havarti on each piece of bread, top with a few leaves of spinach and top with a mound of roasted veggies.
Return to the oven under the broiler and let the cheese get melty. Keep a watchful eye, so you don't end up with burnt sandwiches.
Remove from the oven and flip one side onto the other, cut in half, and enjoy!
Notes
Note: depending on your preference, you may be able to get three sandwiches out of this recipe, in which case you would need 6 pieces of bread, and slightly more butter.