First, prepare the white sauce: Heat butter and olive oil in a pan or saucepan on a low flame. Let the butter melt, then add minced garlic.
Saute the garlic for a few minutes on a medium flame until fragrant. Do not let the garlic change its colour to brown.
Add wheat flour and mix it well on a low flame. Whisk the flour continuously using a wire whisk. Cook the flour for a few minutes until it smells aromatic and changes its colour. You don't need to brown the flour much.
Then add in the milk. Slowly add milk and whisk everything continuously so that no lumps form.
Add salt, black pepper powder, capsicum, and bell peppers. Mix everything and let the sauce simmer for 3-4 minutes until it thickens.
The sauce will thicken as it simmers. Check with the spoon; if it is coating the back of the spoon well, it means it's done. Turn off the heat and add coriander leaves. Mix it well and let it cool down to room temperature.
Preheat the Air fryer or Oven to 180 C.
Take a khari puff and split it into two parts. Apply white sauce generously on the top.
Add cheese on the top and sprinkle the seasonings.
Arrange them on a tray and air fry, or bake them for 5-6 minutes until the cheese melts and becomes nice and crisp.
Puff bites are ready to serve. Arrange them on a serving plate and enjoy it hot.