Prepare outdoor grill with medium-hot coals, or heat gas grill to medium, or see Broiler Method, following. Have grill basket or mesh rack ready, if grid has large openings.
In small bowl, whisk together vinegar, sugar and oil.
Halve and pit peaches. Cut each half into 4 slices for a total of 24. Add to vinegar mixture; let stand 15 minutes.
Meanwhile, in medium-size bowl, beat together heavy cream and sugar until medium-soft peaks form. Beat in ricotta, lemon rind and cinnamon. Spread over dessert shells or Bavarian sponge cake.
Place peach slices in grill basket or on grill grid. Grill until slightly softened, but not mushy, 1 to 2 minutes per side. Arrange 2 slices on top of each cake shell or on Bavarian cake in concentric circles. Serve immediately, or chill for up to 1 hour. Makes 12 servings.
Heat broiler. Arrange peach slices on broiler-pan rack. Broil about 4 inches from heat until lightly charred on top, 2 to 3 minutes.