Heat oil in a large skillet over medium-high heat. While the oil is heating, thoroughly pat the scallops dry with paper towels and generously season with salt and pepper. Once the oil is hot, carefully place the scallops in the skillet and sear, about 1 minute per side or until golden brown. Remove from the skillet and set aside on a clean plate.

Add garlic, sun-dried tomatoes, and spinach to the skillet and sauté until the garlic is fragrant and the spinach has begun to wilt, about 2 minutes. Add the milk, yogurt, and dijon to the skillet and stir to combine. Reduce heat to medium-low and bring the mixture to a low simmer, stirring frequently. Cook for 3 minutes or until the spinach has wilted and the sauce has thickened slightly. Keep warm.

Heat olive oil in a large skillet or saucepan over medium heat. Once the oil is hot, add the onions and garlic and sauté until the onions are translucent, about 3 minutes. Add the grated cauliflower, stir to combine, and continue to sauté for another 3 minutes. Add the vegetable broth and bring to a simmer. Once the vegetable broth has mostly evaporated, remove the skillet from the heat, and stir in the parmesan cheese. Season the cauliflower risotto to taste with salt and pepper.

About 3 minutes before serving, return the seared scallops to the skillet with the creamy spinach-tomato sauce, cover, and reheat until just warm.

To serve, divide risotto between plates or bowls and top with scallops and sauce.