Make the filling: drain tuna cans and transfer to a large bowl.
Chop an onion, heat 1-2 tablespoons of olive oil in a small-medium pan. Add chopped onion and sauté until golden.
Add the onion into the tuna bowl.
Crumble feta cheese. Add eggs and mix well. Add spices and mix again. Set aside
Preheat oven to 350F (180C).
Make the cups: grease muffin tin with olive oil. Lay 4-5 phyllo sheets. Then cut phyllo sheets into rectangles that are wider than the muffin cups.
Create the cups by layering each muffin cup with 3 layers of phyllo rectangles, brush with olive oil in between the layers.
Fill each cup with tuna filling and bake for about 20 minutes. Bake first 10 minutes covered with aluminum foil, then remove the foil and bake for another 10 minutes or until the dough is golden and filling is set.
Allow to cool in the pan for 10 minutes, then remove from the pan and serve.