In small saucepan melt butter over moderate heat, stir in graham crumbs, and then divide mixture among 4 paper lines 1/2 cup muffin tins, pressing in to form a crust. Bake the crusts in the middle of a preheated 350F oven for 5 minutes, and then let cool on a rack for 5 minutes.
In a bowl with an electric mixer, beat together the cream cheese, 1/4 cup of the sugar, the zest and the vanilla until the mixture is combined well. Add the egg, and beat in until well combined, and divide the batter among the tins. Bake the cheesecakes in the middle of a preheated 350F oven for 20 minutes or until they are set, and let them cool on a rack for 10 minutes.
While the cheesecakes are baking, in a small bowl dissolve the cornstarch in the reserved pineapple juice. In a small saucepan simmer the crushed pineapple with the water anb remaining 1 tsp sugar for 5 minutes, or until the liquid is reduced to about 2 tablespoons. Stir the cornstarch mixture and stir it in to the pineapple mixture. Simmer the sauce, stirring, for 2 minutes, transfer it to a metal bowl set in a larger bowl of ice and cold water, and let it cool, stirring occasionally.
Spoon the sauce onto 2 plates and invert the cheesecakes onto the sauce, discarding the paper.