Preheat oven to 375°F/ 190°C, Gas Mark 5.
Thinly slice the potatoes from the casserole pack.
In a medium pan add the butter, garlic and vegetables, saute for around 3 -4-minutes.
Remove the vegetables and set aside.
In the same pan, melt 2 tbsp butter.
Mix in flour until all of the butter is absorbed.
Gradually whisk in milk until the sauce is smooth.
Add salt and pepper.
Stir and heat until sauce is thick and smooth.
Add vegetables to the white sauce.
Add sliced cheese, leaving some for the top of the dish.
Mix together thoroughly.
Bake, covered for 30 minutes. Uncover and bake another 25 to 30 minutes until vegetables are tender.
Garnish with fresh chives or parsley