Kumquat Jam Bars

For the jam:

Whisk together one cup of the sugar with the pectin and salt and set aside. Put the kumquat slices, orange juice, remaining cup of sugar, vinegar, vanilla bean seeds, and cinnamon stick in a large pot and warm over medium-high heat. Add the pectin mixture, stirring to make sure it is completely blended. Bring mixture to a boil. Stirring constantly, boil the mixture until it is thick and coats the back of a wooden spoon, about three minutes. Pour into a heatproof container and let cool to room temperature. Cover and refrigerate until ready to use.

The jam can also be made ahead and frozen for up to six months.

For the dough:

Preheat oven to 350°F. Line a nine-by-13-inch baking pan with parchment paper.

Whisk together the flour, baking powder, and salt. Put the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and beat on medium speed until light and fluffy, about three minutes. Add the egg yolk and vanilla extract and mix until combined, scraping down the sides of the bowl. Add the flour mixture and mix until just combined.

Spoon bits of dough to completely cover the bottom of the pan (about two-thirds of the dough). Don’t pat down. Bake until lightly browned, about 15 minutes. Spread the jam over the baked layer and top with spoonfuls of the remaining dough. Bake until golden brown, about 20 minutes. Put the pan on a cooling rack and let cool to room temperature.

Cut three-by-three-inch bars. If not being served immediately, the bars will keep in a tightly covered container for up to two days. Dust with powdered sugar before serving.

The bars may be made ahead and frozen for up to two weeks. Let come to room temperature and dust with powdered sugar before serving.