Preheat your oven to 350°F. Grease an 8-inch square baking pan, then line with crisscrossed sheets of parchment paper, greasing in between the paper and leaving parchment paper overhanging all four edges of the pan. Set the pan aside.
Make the cranberry jam.
In a medium-sized, heavy-bottom saucepan, place the cranberries, sugar, water and salt, and mix to combine. Place the saucepan over medium heat and cook, stirring occasionally, until the berries have all softened and the jam is thick (about 10 minutes). Set the jam aside to cool.
Make the bar dough.
In a large bowl, place the flour, xanthan gum, oat flour, baking powder, baking soda, salt, cinnamon and nutmeg, and whisk to combine well. Add the butter, and toss to combine in the dry ingredients. Add the brown sugar and almonds, and mix to combine. Add the milk, and mix to combine. The dough should hold together when squeezed with a clean, dry hand.
Transfer half of the bar dough to the prepared baking pan and press firmly into an even layer in the bottom of the pan. Scrape the cranberry jam on top, and smooth into an even layer. Top with the remaining bar dough in an even layer, and press firmly to adhere.
Bake the bars.
Place the baking pan in the center of the preheated oven and bake until golden brown all over (about 40 minutes). A toothpick test won’t work with this recipe, as the jam in the center will always be moist, so it’s best to go by the color of the bars. Remove from the oven and allow to cool completely in the baking pan (at least 1 hour).
Once cool, remove the bars from the pan by holding onto the overhung parchment. Slice into 9 large bars with a sharp knife and serve.