In a large bowl, beat butter and confectioners' sugar with an electric mixer until creamy, 5 to 6 minutes. Add vanilla and salt beating to combine. In another bowl, whisk together flour and cornstarch. Add flour mixture to butter mixture, beating to combine. Add rosemary, beating to combine. Shape dough into a disk, and cover with plastic wrap. Refrigerate for 2 hours. Preheat oven to 350º. Line baking sheets with parchment paper. Set aside. Scoop dough into 1-inch mounds. Roll mounds into balls: place on prepared pans, spacing 2 inches apart. Using a wet fingertip, press to make a small indentation in the middle of each cookie. Spoon approximately 1/2 teaspoon Raven's Nest Cinnamon Pear Jam into each indentation. Bake until lightly browned, 12 to 15 minutes. Let cool on pans for 5 minutes. Remove from pans, and let cool completely on wire racks. Store in an airtight container for up to 5 days.
