In a 10 inch cast iron skillet, melt the butter for the topping over low heat and stir in the Sucanat or coconut sugar. Whisk almost constantly, pausing to check for a small simmer. Once the Sucanat is dissolved into the butter almost completely, turn off the heat and set the pan aside. Low heat here is essential.
In a small to medium sized mixing bowl, whisk together the flour, almond flour, baking powder and salt. Set aside.
Using an electric mixer on high speed (mine was a stand mixer - they are easiest), beat the butter. Then add the sugar and lemon zest. Beat for approximately 4 minutes. The butter should be nice and soft/fluffy when it's done.
On medium speed, beat in the eggs, one at a time.
Slow down the mixer to low speed and mix in the flour and milk. Scrape the sides of the bowl with a spatula occasionally to incorporate everything well. Once everything is combined, stop mixing. Mixing this too much is not a good idea.
Pour the cranberries over the melted butter in the pan, making sure to spread them out enough to all be in a single layer.
Transfer the cake batter to the pan and spread the batter evenly over the cranberries. (A recessed spatula works great for this!)
Place the entire skillet into the oven for approximately 45-55 minutes. A knife should pull out clean when inserted into the middle of the cake.
Run a knife or hard spatula around the edge of the cake to separate it from the sides of the pan.
Cool for a few minutes and then place a platter upside down over the pan. Holding the pan and platter together with pot holders to protect your hands, flip the cake out onto the platter.
Serve with some homemade whipped cream.
Notes
Please note that the nutrition data below is a ballpark figure. Exact data is not possible.