Add toast to WildSide jar and secure lid. Press "Pulse" 6–8 times or until desired crumb size is reached. Set aside bread crumbs.
In large skillet, sauté spinach in ½ tablespoon oil until spinach is wilted.
Add spinach, buttermilk, eggs, potatoes, garlic, salt, pepper, Parmesan cheese, and bread crumbs to WildSide jar. Secure lid and select "Sauces." Add feta cheese, and use spatula to incorporate.
Preheat oven to 400°F. Heat 1 tablespoon oil in skillet or griddle. Spoon approximately ⅓ cup potato mixture onto skillet. Cook each side of potato cake until golden brown, approximately 1–2 minutes. Place each cake onto baking sheet lined with parchment paper, and bake for 10 minutes.