Preheat the oven to 425 degrees F. Line a baking sheet with parchment paper and lightly brush the parchment paper with olive oil. In a food processor, pulse the sweet potato, oats, and salt until very finely chopped and the mixture starts to come together, about 30 seconds. Add the egg and pulse until combined.
Transfer the sweet potato mixture to the prepared baking sheet and, using a spatula, spread into a 10-inch circle about ⅛-inch thick. Be sure to spread evenly—if the center is too thick, it won’t cook through. Brush the top of the circle with 2 tablespoons olive oil and bake until golden on the edges, 30 to 35 minutes.
Once the crust is baked, remove the baking sheet from the oven and, using the parchment paper, carefully flip the crust upside down. Remove the parchment paper and discard. Then, brush the crust with 2 tablespoons olive oil and evenly sprinkle with Fontina.
Return the baking sheet to the oven and bake until the cheese is melted and golden in spots, about 5-7 minutes more. Then, remove from the oven and set aside.
In a medium bowl, combine the lemon juice and remaining tablespoon olive oil. Add the kale, toss to coat, and season with salt and pepper.
Pile the kale salad on top of the crust and sprinkle with the almonds and Parmesan. Garnish with some lemon zest, slice, and serve.