For the scones: Place an oven rack in the middle of the oven. Preheat the oven to 375 degrees F. Line a baking sheet with a silpat or parchment paper. Set aside.
In the bowl of a food processor (see Cook's Note), pulse together the flour, sugar, baking powder, rosemary, salt, and butter until the mixture resembles a coarse meal. Transfer the mixture to a medium bowl. Gradually stir in the cream until the mixture forms a dough. On a lightly floured work surface, roll out the dough into a 1/2-inch thick, 10-inch circle. Using a 3-inch heart-shaped cookie cutter, cut out heart-shaped pieces of dough and put on the prepared baking sheet. Gently knead together any leftover pieces of dough and roll out to 1/2-inch thick. Cut the dough into more heart shapes and add to the baking sheet. Using an index finger or a small, round measuring spoon, gently make an indentation in the center of each pastry heart. Spoon a heaped 1/2 teaspoon of jam into each indentation. Bake for 18 to 20 minutes or until the edges are golden brown. Transfer the cooked scones onto a wire rack and cool for 30 minutes.
For the glaze: In a medium bowl, mix together the lemon juice and powdered sugar until smooth. Gradually add the water until the mixture is thin enough to spread. Using a spoon, drizzle the glaze over the scones. Let the glaze set for about 30 minutes. Serve or store in an airtight plastic container for 2 days.
Cook's Note: The dough can also be made by hand by stirring together the flour, sugar, baking powder, rosemary, and salt in a large mixing bowl. Add the butter. Using your fingertips or a pastry blender, work the butter into the flour until the mixture resembles a coarse meal. Gradually stir in the cream until the mixture forms a dough.