1. Process raspberries in a blender or food processor until smooth, stopping to scrape down sides. Press mixture through a wire-mesh strainer into a bowl, using the back of a spoon to squeeze out juice. Discard pulp and seeds. Cover sauce, and chill until ready to serve.
2. Place 12 foil baking cups in muffin pans; discard paper liners in cups.
3. Beat whipping cream at medium-high speed with an electric mixer until soft peaks form. Reduce speed to medium-low, and gradually add lemonade concentrate, sweetened condensed milk, and lemon juice, beating until blended. Increase speed to medium-high, and beat until stiff peaks form. Spoon into 12 foil baking cups in muffin pans by heaping 1/3 cupfuls. Freeze at least 1 hour or until whipped cream mixture is firm.
4. Place on serving plates, and let stand at room temperature 10 to 15 minutes or until slightly softened. Serve with Raspberry Sauce. Garnish, if desired.
Note: For testing purposes only, we used Minute Maid Frozen Concentrate for Lemonade. To make ahead, freeze as directed for 1 hour; cover whipped cream mixture in pans or lemon cups with plastic wrap. Wrap pans or lemon cups securely with heavy-duty aluminum foil. Freeze pans up to 4 days and lemon cups up to 1 day.
How to Make a Lemon Cup: Cut stem end off each lemon (top one-third of lemon). Save tops to garnish plates, if desired. Cut a small slice off bottoms of lemons to allow them to stand upright. Run a grapefruit knife around lemon between the peel and pulp, loosening pulp. Scoop out pulp with a spoon. Remove excess juice from inside shells by scraping against the sides with a spoon.