Heat skillet over medium-high heat until oil is hot. Add potatoes and cook until browned. Add peppers and onions and saute until tender.
While the veggies are cooking, whisk together the eggs, milk, salt, and pepper and set aside.
Turn the heat to medium-low, add spinach to the veggies in the skillet, and cook until just wilted, then incorporate the spices and herbs and cook for 1minute.
Slowly drizzle in the egg mixture, making sure to cover the surface evenlywith the egg mixture.
Now add crumbled goat cheese over the top of the frittata.
Cook on the stove top for maybe 5 minutes, or until you just start to see the egg mixture cooking and firming along the outside edges. Just looking for a thin, pale yellow color around the very outside rim of the frittata.
Place the skillet in the oven and cook at 425 for 10-15 minutes, give or take a few. Watch the frittata closely so as to not overcook it. Pull it out when the mixture has set but has a slight jiggle still in the middle, and before it has browned on top.
Let it rest for 5-10 minutes and slice it into wedges to serve!