Flatbread with roasted mushrooms, onions, and asiago cheese

Rustic flatbread (enriched unbleached wheat flour [wheat flour, malted barley flour, ascorbic acid added as a dough conditioner, niacin, reduced iron, thiamine mononitrate, riboflavin, folic acid], water, whole wheat flour, soybean oil, yeast, nonfat dry milk, extra virgin olive oil, sugar, salt, dry sourdough or rye [water, fermented rye flour, salt], enzyme, wheat starch), cheese spread (mayonnaise [soybean oil, water, egg yolk, distilled vinegar, salt, sugar, calcium disodium edta {to protect flavor}, dried garlic, dried onion], mozzarella cheese [low moisture part-skim mozzarella cheese {pasteurized milk, cheese culture, salt, enzymes}, potato starch and powdered cellulose [to prevent caking}, natamycin {a natural mold inhibitor}], asiago cheese [pasteurized milk, cheese culture, salt, enzymes, powered cellulose {to prevent caking}], garlic, parsley), mozzarella cheese (low moisture part-skim mozzarella cheese [pasteurized milk, cheese culture, salt, enzymes], potato starch and powdered cellulose [to prevent caking], natamycin [a natural mold inhibitor]), roasted mushrooms and onions (crimini mushrooms, yellow onions, canola oil and extra virgin olive oil, thyme, sea salt), asiago cheese (pasteurized milk, cheese culture, salt, enzymes, powered cellulose [to prevent caking]), baby spinach.