Pour chicken stock into a small pot and heat it up - keep it on the stove on low heat
To a heated pan add 1 tbs of butter
Add onion and garlic and season with salt
Let it soften for few minutes until the onion becomes translucent and sweet
While onion is cooking - dice mushroom
Add 1/4 tbs of butter to onion and add diced mushroom
Once mushroom brown, add another 1/4 tbs of butter and add rice, stir well
Cook for 2 minutes and add first ladle of hot chicken stock
Stir and cook until the stock gets absorbed but not the point that the rice gets dry
Continue the process till the rice is al dente (not soft, just a bit chewy) - about 15-20 minutes
Add remaining butter and adjust seasoning if needed
Turn off the heat
Add grated parmesan, stir and serve