Cannolis are one of life's fleeting pleasures because they become soggy about 4 hours after they're made. A better solution is to fill only what you need and store the shells and the filling separately for later. Freezing cannoli filling will alter it, but not beyond repair.
Cannoli filling made with ricotta cheese and whipped cream is best stored in the refrigerator in a covered container. Stored this way, it will stay fresh for up to 4 days. When you've had your fill of cannolis, slather the filling on cakes or dip cookies and fresh fruit in it. You can freeze cannoli filling, especially if you stabilize it first, but it won't taste quite the same when you thaw it. Ricotta cheese tends to become watery when frozen, and the whipped cream may lose some of its volume.
To freeze cannoli filling, pour it in a freezer-safe plastic bag or container and seal it tightly. Store it at 0 degrees for no more than a month. The filling remains safe indefinitely in the freezer, but quality declines quickly after a few weeks. To use the filling, thaw the container in the refrigerator overnight. Don't thaw it in the microwave, which will alter its texture, or on the countertop, which promotes bacterial growth. Toss the thawed filling in the bowl of a stand mixer or use a hand mixer to beat the filling. Add a bit of vanilla or other flavorings to freshen it. Whipping the filling gives it a light, fluffy texture and restores separated ricotta cheese.
Stabilize the Stuff
Your best odds at freezing cannoli filling start with the right ingredients. Stabilize the whipped cream with gelatin and the filling freezes quite well. Start by softening -- or blooming -- unflavored gelatin in a bit of cold water. When it has softened and expanded, heat it in the microwave for a few minutes to melt the gelatin granules. Add a bit of heated whipping cream. Whip the whipping cream until soft peaks form. Stir in the gelatin and whip the cream for a few seconds more. Whip the ricotta cheese into the whipping cream, along with any desired flavorings. The gelatin not only helps the filling retain its volume, but can also prevent a watery, grainy texture.
A Word About Flavorings
Many cannoli filling recipes call for the addition of chocolate chips, pureed berries, orange peel, cocoa powder or liquors. These products dress up an otherwise rather ordinary dessert. However, before you freeze cannoli fillings that include additional ingredients, consider how well the ingredients freeze. Chocolate chips and cocoa powder won't cause a problem, but fruit adds moisture to the filling, which can cause it to separate. Some flavorings, such as almond extract or imitation vanilla extract, can become bitter after they've been frozen.