Preheat the over to 350° F. Line an 8 inch pan with parchment paper. If you don't have parchment paper, make sure you grease your pan very well.
In a bowl, mix together the allulose, sea salt, baking powder, and espresso. Set aside.
Put the butter in a pan over low to medium heat. You will want to brown the butter, which takes around 10 minutes. Stir frequently until the liquid has a golden brown color and the milk solids are red/brown hue.
While the butter browns, melt chocolate chips in microwave by setting the timer for 1 minute and stirring every 15 seconds. If your chips still aren't melted, add an additional 10 seconds until they are melted. Set aside.
Once your butter is browned, immediately pour it into the bowl you set to the side with allulose, sea salt, baking powder, and espresso. Mix by hand until combined. Let the mix cool for 5 minutes.
In a separate bowl, combine oat fiber, lupin flour, cocoa powder and almond flour. Set aside.
Whisk your eggs into the batter one at a time, making sure they are well combined. The mix will be very thick and shiny. You will then add your vanilla extract, melted chocolate, and mixture of dry ingredients. Beat together continuously for about 2 minutes.
Pour the mix into a parchment-lined 8“ inch baking dish and place into the oven on the middle rack. Allow brownies to cook for around 30 minutes at 350° F. Time may need to be adjusted depending on your oven and your location. Check to see if the brownies are done by putting a toothpick through the middle of the bake. The toothpick should come out mostly clean. Once the brownies are done, take them out of the oven and let them cool in the pan for an hour or two.
Once the brownies are completely cool, lift them out by the edges of the parchment paper and transfer them to a cutting board. Use a knife to cut the brownies into 16 squares (4X4).