Preheat oven to 350°F.
In a food processor, grind the walnuts (until medium-fine) with the 6 tablespoons granulated sugar and set aside. In an electric mixer, mix the 3/4 cup granulated sugar, the brown sugar, salt, baking powder, and flour until well combine. Add the butter and mix until the mixture clumps, about 1 1/2-2 minutes. Add the vanilla and egg yolks to the mixture and mix for 40 seconds. Pack two-thirds of the dough into the bottom of a 9 by 12-inch ungreased pan and bake until the dough is light brown, 25-30 minutes.
To make the jam, in a heavy-bottomed pot, combine the figs, sugar, lemon zest, thyme, and lemon juice and pour in enough water to cover. Bring to a boil and boil for 10 minutes. Reduce the heat and summer until the figs are tender, about 30 minutes. Remove the thyme. Puree the mixture in a food processor until smooth.
To assemble the crisp, spread the jam evenly over the baked dough. In a bowl, crumble together the remaining third of the dough and the walnut and sugar mixture. Sprinkle the mixture over the fig jam and bake for 50 minutes. Drizzle with Fig Syrup (recipe follows). Makes one 9 x 12-inch crisp.