1. To roast the parsnips: Preheat oven to 425F.
2. Peel the parsnips and cut into thick slices.
3. Toss parsnip slices with 1/3 of the olive oil, salt, and pepper in a large bowl.
4. Spread the parsnips into a single layer on two baking sheets.
5. Roast for 20 minutes, then test for doneness. You should be able to pierce parsnip pieces easily with a fork.
6. Keep in a sealed container in the fridge overnight, or if roasting same day, let cool at least 10 minutes before using in parsnip cakes.
7. To make the cakes: Place 1/2 of the roasted parsnips, spinach, almond flour, eggs, salt, and pepper to taste in the food processor (you will be processing in 2 batches).
8. Remove batter to a bowl and process the other half. Add this batter to the first batch.
9. Heat half of the remaining oil in a large skillet over medium high heat. Scoop heaping spoonfuls of batter into the heated pan and flatten slightly with a spatula.
10. Let cook for about 3 minutes, then flip. The first side should be golden brown.
11. Add remaining oil before frying the next batch. Serve parsnip cakes hot.
12. If desired, freeze by wrapping individually in either plastic wrap or parchment + foil. Then store in a ziplock freezer bag.