Place baby spinach and onion in a food processor fitted with the S blade and pulse to mince finely.
Place frozen corn in a strainer and run water over it for about 30 to 60 seconds to thaw.
Place bread slices on a pizza screen.
Spread 1-2 tbsp. of black bean & cilantro spread on each slice of bread.
Spread 1-2 tbsp. of quick guacamole over black bean spread.
Sprinkle minced greens and onion on guacamole.
Sprinkle thawed sweet corn on top.
Place pizza screen in toaster oven and toast to desired level of crispiness. (I used darkness level 3 for 2 slices – about 3:45 minutes – on my Breville toaster oven.
If cheese sauce was made ahead of time and refrigerated, warm in microwave for about 30 seconds.
Spoon cheese sauce over avocado toast and serve.