In a medium saucepan, melt butter over medium-high heat. Saute leeks and jalapenos until soft. Add garlic and flour, making a paste, continuing to brown for 1 minute. Season with pepper and salt.

Using a fork, whisk in heavy cream and bring to a low simmer. The mixture should become thick, remove from heat, set aside.

Coat your slow cooker with cooking spray or aluminum foil. Start with a layer of potatoes, top with a large spoon of cream, leek and jalapeno mixture and sprinkle and quarter cup of cheddar cheese. Continue until your slow cooker is full. Refrain from topping the last layer with cheddar cheese.

Cover and set for 4 hours on low or 8 hours on high. Thirty minutes before serving, top with remaining cheddar cheese and cover until ready to serve.

Pierce potatoes with a knife to make sure they are soft. Cheese should be melted and bubbly. Serve your Fleming's Slow Cooker Au Gratin Potatoes.