Heat 1 tbsp olive oil in a non stick pan. Add 1 tbsp butter and let it melt. Add refined flour and saute till the raw smells disappear.
Take the pan off the heat and gradually add milk, stirring continuously in order to avoid lumps. Cook till the sauce thickens. Add salt and black pepper powder and mix well.
Add 2 tbsps grated cheese and mix well. Transfer into a bowl and set aside to cool. Heat 1 tbsp olive oil and 1 tbsp butter in another non stick pan. Add garlic and mix.
Add onion and saute. Add red capsicum and yellow capsicum and continue to saute till onion turns a light brown.
Arrange the canapés in a serving platter. Put 1 tbsp cheesy white sauce in each canapé, top with 1 tbsp of mixed vegetables and sprinkle a little grated cheese on top.
Grill in preheated oven at 180°C for 5-7 minutes. Serve hot.