Pre-heat oven to 350 degrees and spray a muffin tin with cooking oil.
On a parchment paper or Silpat-lined baking sheet, scatter shredded cheddar in small circular mounds, spaced at least an inch apart.
Bake at 350 degrees for about 8-10 minutes, when cheese is just turning golden.
After removing from oven, let sit for 30-60 seconds and then lift cheddar rounds with spatula and fit into muffin tins. Press down to form cheese into cups. It's important wait 30-60 seconds before moving, so cheese isn't gooey, but then you must work quickly before it hardens completely.
Cool completely and then remove from muffin tin.
Spoon or pipe avocado feta mousse into each cup and top with crumbled baked kale.