Pulse the cauliflower florets in a food processor in several batches to make coarse crumbs, about the size of rice (see Cook's Note). You should have 6 to 7 cups of riced cauliflower.
Heat the olive oil in a large skillet over medium-high heat. When the oil is hot, add the scallion whites and cook until wilted and slightly golden, about 2 minutes. Add the riced cauliflower, 1 teaspoon salt and a few grinds of black pepper; stir to coat the cauliflower in the oil. Cover and cook, stirring occasionally, until the cauliflower rice is tender but the pieces are still separate, 6 to 7 minutes.
Meanwhile, toast the almonds in a small skillet over medium heat until golden, tossing frequently, about 3 minutes. Set aside.
Remove the cauliflower from the heat and stir in the scallion greens, parsley and toasted almonds. Transfer to a large bowl and serve.
To get nice, even-sized cauliflower "crumbs" with no lumps, fill the food processor no more than half full with florets. Depending on the size of your food processor, you may need to pulse the florets in up to 5 batches.