Place the squash, eggs, coconut flour, arrowroot flour, jalapeño, salt, and baking powder in a large mixing bowl. Stir until combined. Let mixture sit for 5 minutes.
Heat a large sauté pan over medium heat for 1 minute. Add the butter and olive oil and swirl to coat the bottom of the pan. Spoon 1/4 cup portions of the squash mixture into the sauté pan (I like to use a large ice cream scoop and press the fritters down so they are flat and about 3/4-inch thick. Fry the fritters until golden brown on the bottom, about 2-3 minutes. Using a spatula, flip the fritters and continue cooking until they’re golden brown on the second side. Serve with sour cream, green onion and lemon juice.
Note: I only test the recipes on my site with the listed ingredients and measurements. If you would like to try a substitution, you are welcome to share what you used and how it turned out in the comments below. Thanks!