A spinach and ricotta quiche is a dish rich with eggs and cheese, so I think this Meatless Monday recipe deserves a wine pairing with some heft. A California Chardonnay would be a nice match, though not one too aggressively oaked. I'd look to one of my favorites not from Napa, but from the Santa Cruz Mountains: Mount Eden Vineyards. They make a gorgeous Chardonnay that would compliment this quiche. There are plenty of examples from Oregon as well that show a little restraint but still have the depth and substance to handle all that dairy.
You could also go in another direction and contrast the richness of the spinach and ricotta quiche with something a bit more lively. The Sancerre region of France's Loire Valley is home to the world's top Sauvignon Blancs; they are a richer style of Sauvignon Blanc that won't get overwhelmed by the eggs and cheese. (I also think Sauvignon Blanc goes well with greens like spinach.) And please consider two of the world's most versatile wines you can buy: dry sparkling and rosé. Especially if you're having this quiche for lunch, and want to make your lunchtime a little more awesome.