Preheat oven to 375°F with a rack in the center.
Wash the ramps or leeks well. No need to dry. Trim the ends and slice. Heat the olive oil a large frying pan over medium heat. Add the ramps or leeks, along with half the salt. Sauté for about 3 minutes for ramps, 10 minutes for leeks, until tender.
If using frozen spinach, cook according to package directions and drain thoroughly, squeezing out as much excess water as possible, before proceeding. If using baby spinach, add it to the skillet and cook until wilted. Let cool slightly, and if there is any excess moisture, drain it.
Combine the cream cheese, sour cream, mayonnaise, remaining salt, and pepper in a large bowl or the bowl of a stand mixer or food processor. Mix or pulse until well combined.
Add the sun dried tomatoes, parmesan cheese, leeks or ramps, and spinach and mix to incorporate well.
Spread the dip into a medium oven-proof dish and sprinkle with the Pepper Jack cheese.
Bake for 25 minutes, until the cheese is melted and browned around the edges and the dip is starting to bubble a bit. Cool slightly before serving.