Take even number of mushrooms and remove their stems.
Finely chop the stems and keep aside.
Take a pan and heat 1 tsp of oil in it.
Add cumin seeds and let them splutter.
Add garlic and let it turn golden brown.
Then add onion & green chilly. stir.
Add the chopped stems of mushrooms and saute for a minute.
Add spinach, salt and coriander powder.
Roast spinach on low heat till it tuns dry and well cooked.
Once done, switch off the heat and keep aside to cool it completely.
Now pick mushroom button one by one and fill the hollow side with spinach mixture.
Keep the mushrooms in a pair, taking into consideration their size. Preferably make a pair of two equal sized mushroom buttons.
Now pick the first pair of mushroom buttons, bring the filled side of both the mushroom buttons against each other and pierce the mushroom with a toothpick, holding them together. Repeat the process with all the pairs. Keep aside.
Take a bowl, add flour, pinch of salt and black pepper. Make a thick paste with the help of water. Keep aside.
Dip each pair of mushroom in the flour paste and fry in hot oil until turn golden brown.
Remove them on paper napkin to release excess oil.