In food processor fitted with metal blade, beat the sugar and almond paste until almond paste is chopped into small bits. Add butter; pulse just until blended. Add eggs and vanilla; blend until smooth. Scrape down the bowl. In a separate bowl, whisk the flour, baking powder, and salt. Add to the butter mixture and pulse until just blended. Cover and chill while preparing crust.

For crust: With electric mixer, beat butter and sugar until light and fluffy. Scrape down the bowl, then beat in the egg yolk. Combine the flour and salt, then add to the bowl, beating on low speed until just incorporated. Place dough in a 9-inch round fluted tart pan. Using fingertips, press the dough evenly across the bottom and up the sides of the pan to cover in an even layer. Dock (prick) the dough every 2 inches with a fork. Place the tart pan on a baking sheet; freeze for 10 minutes or until firm.

Meanwhile, set a rack in the top third of the oven and preheat to 350°. Spoon the frangipane to the center of the tart crust, and using an offset spatula, spread evenly all the way to the edges. Individually place the chunks of rhubarb on the frangipane in a pattern you like, leaving room between the pieces. Sprinkle tart with 1 tablespoon of sugar.

Bake until the top is lightly browned, about 40 to 45 minutes. Tart will look puffy, but then settle with cooling. Cool completely.