Creamed cassava with lemon parsley gremolata

2 lbs cassava
1/2 cup milk
2 tbs butter salt
For the gremolata:
1 tsp lemon zest, finely grated
2 cloves garlic, minced
1/4 cup finely chopped parsley
Boil cassava in lots of water for about 20 to 30 minutes, until very soft, drain and remove inner core.
Heat milk with butter.
Add to drained cassava and crush cassava until creamy.
Add gremolata and stir.
Serves four or six