Combine the roquefort, cream cheese, shallot, garlic, Worcestershire sauce, pepper, and thyme in a food processor and process until smooth, scraping down the sides as necessary. Transfer to a small bowl and chill thoroughly before proceeding.

When the mixture is thoroughly chilled, portion into small balls about 2 teaspoons each (a small portion scoop works well for this purpose). Place the chopped walnuts in a small bowl and roll the cheese balls in the nuts, pressing to adhere to all sides and rolling between your hands to make them uniformly round. Refrigerate or freeze briefly until ready to serve.

Place cheese truffles on a serving plate or platter, along with slices of apples, pears, and grapes. Croustades may also be served alongside if desired.