Preheat oven to 350 degrees F. Grease a 10 inch round pie plate or 9x9 inch square baking dish with butter.

Peel the potatoes and and slice them thinly.

In a large saucepan or dutch oven, melt the butter and saute the garlic for just a minute or so until it softens but does not brown.

Add the whipping cream, milk and salt to the softened garlic and gently bring to a slow simmer over medium heat.

Add the sliced potatoes and bring to a slow simmer once again. Simmer, uncovered, for 5 minutes.

Using a colander or coarse sieve, drain the potatoes but reserve the cream and milk mixture.

To the reserved hot cream and milk mixture, stir in 2 tbsp French's Dijon Mustard until well blended.

Arrange half of the potatoes in the bottom of the prepared baking dish. Sprinkle on a small pinch of black pepper, 1/2 of the chopped thyme and half of the Gouda cheese.

Pour half of the cream mixture over the potatoes.

Arrange the second half of the potatoes on top, followed by the pepper, thyme, cheese and cream mixture, as in the first layer. Do not overfill the baking dish with the cream mixture. Make sure the liquid level is 1/2 inch below the top.

Place the baking pan on a parchment paper lined cookie sheet to catch any spill over that may occur and bake for approximately 1 hour or until the top is a medium golden brown and the bubbling sauce appears to have thickened.

Let the potatoes rest for 10 -15 minutes before serving.