Makes about 12 Newtons
For the Fig Filling:
For the Cookie Cake Dough:
First make the fig jam filling. Place figs, water, orange, brown sugar, lemon zest and salt in a large saucepan. Simmer over medium-low heat for about 30 minutes or until the figs have all lost their shape and are soft and jammy. Remove from the heat. Stir in the vanilla. Using a blender or an immersion blender, blitz the sauce until it's in a rough chunk or to suit your taste. Allow the jam to cool for 2 hours or until it's at room temperature. This can be made ahead up to 2 days in advance, covered and refrigerated.
For the dough, using a stand mixer with the paddle attachment, cream together the butter and sugars on medium speed until light and fluffy. Scrape the sides of the bowl a few times to make sure it's all incorporated. Beat in the egg yolk and vanilla on medium speed until combined. In a small bowl, sift together the flours, baking powder and salt. Then, slowly add the flours mixture to the butter-sugar mixture on low speed until it is fully incorporated. Scrape the sides of the bowl to make sure everything is mixed in. Turn the dough (it will look and feel like cookie dough) onto a sheet of plastic wrap and refrigerate for at least 30 minutes (or for up to 2 days) until it's firmed up but can still be shaped.
Preheat the oven to 350 degrees Fahrenheit. Place the cooled dough onto a big sheet of parchment paper that has been agressively floured. Roll slash shape the dough into a rectangle roughly 9 inches by 16 inches and about 1/4 inch thickness. Make sure nothing it sticking to the parchment or the rolling pin. Scoop the fig jam along the center of the dough, lengthwise, in a strip about 2 1/2 inches wide. Using the parchment, gently fold one side of the dough over the fig strip and then the other side of the dough over the fig strip (see photos) so they meet in the middle. Pinch the sides together to create a fig log. Then, using the parchment turn the dough onto a fresh pan lined with parchment paper so that the log is seam-side down. Brush away or remove any excess flour on the log. At this point, you can actually store the fig log, tightly wrapped, in the fridge for a day or so or in the freezer for up to 2 weeks.
Bake the fig log for 45-70 minutes (depending on how cold it is, room temperature, fridge or freezer) or until it's golden brown all over. There may be some oozing fig juice. This is fine slash awesome. Yum! Cool the Newton log on a wire rack for 2 hours or until it is entirely at room temperature. Slice into 1-inch thick Newtons and enjoy!
PS- We think it could also be fun to brush a simple egg wash over the uncooked fig newton log and sprinkle with demerara sugar before baking. Just a thought...