If you'd like for the frosting to be a little thicker and more stable, you can add more powdered sugar or up to 1 Tablespoon Instant Clearjel (a tasteless modified cornstarch that thickens instantly). However, you will need to whisk the Instant Clearjel with at least equal parts powdered sugar before adding it to the frosting to avoid clumping). This will thicken the frosting, but cream cheese frosting naturally doesn't have the same fluffiness and stability as a traditional frosting. My go-to frosting for piping is a delicious cream cheese/ buttercream blend--it's my Vanilla Bakery Buttercream.