Preheat oven to 350F. Butter and flour a 13x9-inch baking pan. Combine chocolate and butter in a heavy saucepan and melt over low heat, stirring frequently. Cool and pour into a mixing bowl. Stir in 3/4 cup sugar. Whisk in 3 eggs, one at a time, 2 teaspoons vanilla and salt. Stir in 3/4 cup flour and pour into the prepared pan. In a bowl cream together cream cheese with 1/2 cup sugar with an electric mixer at medium speed until fluffy. Beat in lemon juice, 1 egg, 1/2 teaspoon vanilla, and 2 tablespoons flour until smooth. Spread in an even layer over brownie batter. Sprinkle with berries and bake 35 to 40 minutes, or until top is puffed and tester comes out with crumbs. Cool in pan on rack. Chill to set. Cut in squares and wrap in plastic.
