Potato and Mushroom Gratin with Goat’s Cheese | Rachel's | Umami

Ingredients

• 1/2 tablespoon butter
• 125 g mixed mushrooms, (trimmed and sliced)
• 1 shallot, (finely chopped)
• 300 g medium-starch potatoes (e.g. Linda), (scrubbed clean, about 4 medium)
• 1 tablespoon olive oil, (plus more for the baking dish)
• 75 g fresh goat cheese, (divided)
• Sea salt and freshly ground black pepper
• 1/8 cup whole milk (60 ml)
• 3 tablespoons freshly grated Parmesan cheese (30 g)
• 1/2 teaspoon fresh thyme leaves