Sprinkle the grated Parmesan in a thin layer forming a circle. The circle should be a bit bigger than your shot glass bottom.
Cook for about a minute, until the cheese melts and becomes golden.
Carefully peel the cheese circle off the pan and quickly place it on the shot glass bottom (golden side up). Gently press the cheese around the glass to shape a basket and leave it to cool for about a minute. Repeat with the remaining cheese.
Fill the baskets with tuna and mayo and sprinkle with crushed chili