Preheat oven to 350 degrees fahrenheit.
Arrange sliced potatoes in an oven safe dish or cast iron skillet, set aside.
In a saucepan, heat butter over low heat. Once butter begins to melt, slowly stir in cornstarch, fresh herbs, and salt and pepper until smooth.
Add onions, shallot, and garlic. Cook on low for another 2-3 minutes.
Slowly add non-dairy milk and bring to a boil. Stir constantly until the sauce has thickened, about 3-5 minutes.
Reduce heat to low and add in the cheese cube, stirring until they have formed a creamy "cheese" sauce.
Pour sauce over the sliced potatoes, cover and bake in preheated oven for 1 hour. Uncover and bake an additional 45 minutes (for extra crispiness and cheesy bubbliness, we broiled them the last five minutes).
Serve warm garnished with fresh chives.