Preheat oven to 350F, spray a 9x13 casserole dish with cooking spray.

Peel and slice your potatoes into very thin circle slices, as thin as you can get them.

In a pan on the stove over medium heat melt your margarine, add in flour and mix, then whisk in milk. Stir often until sauce thickens, this could take about 10-15 minutes. Then stir in your oregano, dash of salt and pepper, 3 Tbsp of ranch dressing (leave 2 Tbsp aside for top) and your cheese, stir well til cheese is melted.

Use half of your potatoes and layer them on the bottom of your dish. Sprinkle half of your chicken (4oz) and 2 Tbsp of your bacon bits on top of potato slices. Pour half of your cream mixture over top.

Layer remaining potatoes, chicken and bacon bits, then pour remaining sauce on, top with your remaining 2 Tbsp ranch. (To evenly spread the ranch I placed mine in a small zip lock bag, cut of end and drizzle over dish)

Cover with foil and bake in oven for 65 minutes. Cut into 6 equal portions