Place the cheese and cornflour in a bowl and toss to coat.
Melt butter over medium heat in a small pot.
Add garlic and onion and cook slowly for 3 minutes or until onion is translucent but not browned.
Add the tomato (including juices) and cook for 2 minutes until tomato is slightly softened.
Add the evaporated milk and the cheese. Stir, then add chilies and spices.
Stir until the cheese melts and it becomes a silky sauce.
Add salt to taste - amount required depends on saltiness of cheese used.
Add and stir through the coriander.
Stir in milk to adjust consistency (I use 2 tbsp) - the dip thickens when it cools, and milk can be added later to adjust to taste.
Remove from heat. Serve warm or at room temperature - it will be soft and scoopable even when it cools.
Store in the refrigerator. To reheat add a small amount of milk to adjust the consistency as desired. If you add too much, just leave it in the stove for a bit longer.