Reserve 4 berries for garnish and divide the remaining berries among four 8-ounce mason jars or tempered glasses.
Put 2 cups of the cream and 1/2 cup of the sugar in a small saucepan. Split the vanilla bean, scrape the seeds into the cream and drop in the bean halves. Bring the mixture to a boil over medium to medium-high heat and boil for 4 minutes, stirring occasionally and taking care that it doesn't boil over (which can happen really easily). Remove from the heat, discard the vanilla bean halves and stir in the lemon juice.
Divide the cream among the glasses (the berries will float up to the top). Refrigerate until set, at least 3 hours or overnight.
Before serving, gently whip the remaining 1/2 cup cream with the remaining 1/2 teaspoon sugar, and dollop over the possets. Top each serving with one of the reserved raspberries. (If you serve the possets the next day, you can let them warm for 20 minutes or so at room temperature before serving.)
From Food Network Kitchens