Add water in a pan, bring to boil
Add broccoli, cook for 2~3min
Drain and keep aside
Blanch spinach for a min
Rinse under cold water, drain
Melt butter in a pan
Add garlic sauté for a min
Add flour, stir and fry for 2min
Add milk little by little while stirring
Add half of cheese, pepper powder, broccoli, spinach and stir well
Fill this in a ovenproof dish
Top with mashed potato and remaining cheese
Pre-heat oven to 180°C
Bake for 25~30min