For the Chili Relleno Bake:
Butter or spray cooking spray in a 13x9 inch-baking dish.
Use an immersion blender or mixer to beat together eggs, milk, flour, and salt & pepper. Set aside.
Arrange chilies in bottom of baking dish to cover entire bottom of the pan. Cover with a layer of ½ of the cheese, then add another layer of chilies, then finish with remaining cheese.
Pour egg mixture over the top of chili mixture.
Bake in a preheated 350-degree oven until casserole is puffed and turning golden brown on the edges. Center should be set and a knife inserted in center should come out clean. This will take around 40 minutes, but it’s a good idea to start checking at about 30 minutes.
For the Grilled Tomatillo Salsa:
Toss the tomatillos, garlic, chilies, and onion with oil and sprinkle with salt. Grill in a grill basket over medium high heat until tomatillos and garlic are softened, onions are softened and slightly charred, and peppers are charred.
Allow to cool and remove skins, seeds, and membranes from the chilies. Chop chilies, onion, and garlic finely. Remove stems from tomatillos and chop coarsely.
Toss with oil and salt. Taste and add agave if you need to add some sweetness. If you like a ‘juicer’ salsa, mash with a potato masher until the consistency you like.