In a small bowl, add the 2 tbsp warm water, yeast and inulin and use a fork to gently stir everything together. Cover with saran wrap and set aside.
In a large bowl, whisk together all of your dry ingredients including; vital wheat gluten, allulose sweetener, oat fiber, lupin flour, coconut flour, baking powder, xanthan gum, cinnamon and salt.
Next, chop the cold butter into rough small chunks (they don't have to be even) and add them to the bowl.
Use a fork or dough blender to cut the butter into the dry ingredients and make the pieces smaller. (I like to use the end of the fork to poke down on the pieces. This may take a bit. Don't worry about the pieces being perfectly small!)
Once the pieces are about the size of mentos as I like to say, you can then add the cold water and heavy cream, along with the yeast mixture from earlier (which, should now be quite foamy).
Stir everything until the dough starts to come together, then use your hands to form a rough ball. Our goal is not to fully blend the dough, but simply to get it to stick together in a ball shape with chunks of butter still easily visible. Add an extra tablespoon of cold water only if needed.
Next, wrap your large ball of dough in plastic wrap and place it in the fridge to chill for 30min -1 hour.
Meanwhile we can make the almond paste. Add all of the almond paste ingredients to a bowl, then mix well(a hand mixer works best for this) until everything is combined. Then cover and refrigerate until you need it.
After 30min - 1 hour, you can un-wrap the ball of keto croissant dough and place it on a greased and lightly vital wheat gluten-floured surface. (I prefer to use two pieces of greased and floured parchment paper for this). If not using parchment paper on the bottom, at least use one piece on top of your dough. This will prevent the rolling pin from sticking to the dough.
Roll the dough out length-wise to get a long rectangle. Fold one side of the dough inwards, then the other like folding a brochure or letter. Gently push any rough edges in to straighten out the shape of your dough. Then turn it 90*. flour the surface and top of the dough again and repeat the first step of rolling it out into a long rectangle..then again fold it like a letter. Repeat this process 4-5 times in total. Your dough may get tough to roll out. If this happens, simply refrigerate and cover the dough for another 30min - 1 hour to allow the gluten time to relax.
After these initial 4-5 folds, refrigerate your dough for 1 hour. Then repeat for 2 more folds or just until your butter is almost completely blended and streaky rather than chunky. If your dough is super tough to roll, you can roll it into a thick rectangle and cut it in half. Then roll out each half separately to make the process easier.
Once you are done with rolling and folding, make sure your dough chills for at LEAST 30min or preferably 1-2 hours prior to the next step.
Pre-heat your oven to 350*F.
Take your dough out, un-wrap it and slice it evenly in half if you haven't already. Re-wrap one half and place it back in the fridge for later.
Roll out this piece of croissant dough again, but this time, width-wise AND length-wise to create a large thicker rectangle.
Make sure your dough gets about as thin as you can get it. It will likely be about 1/4 of an inch thick (basically thin but still easy to pick up without breaking).
Cut any weird un-even edges off your rectangle using a sharp knife or pizza cutter (save the dough!) Then for LARGE croissants, cut the rectangle diagonally from one corner to the other into 2 long triangles. For SMALL croissants cut the rectangle of dough into 4-6 smaller rectangles (see video for how I sliced smaller croissants).
Use the left-over scraps to form one final large croissant by placing the pieces of dough together and rolling them out to form another rough long triangle. (Or form a couple more croissants if making smaller croissants).
Take the triangles and using a knife or pizza cutter, slice just a bit up the middle of the short FLAT side of the triangle (see photos). Then pinch the corners of this side and gently pull them apart slightly (again, see the photos). This just helps our croissants look prettier after rolling them up. Add a small scoop of almond paste to the bottom of the croissant then roll the croissants from the bottom (cut-side) up to the very tip of the triangle, then gently press the tip of the triangle into the dough to help the croissant hold together. Don't worry if it's not completely sticking just yet. Repeat this process for all of your croissant triangles.
Place finished croissants on a parchment-lined baking sheet spaced evenly apart. Remove your second-half of the dough from the fridge and repeat this same process.
Once you have all of your croissants on a parchment-lined baking sheet, lightly brush all of the croissants with heavy cream. Cover your croissants with plastic wrap. Then let the croissants rise for ~10-15 minutes at room temperature OR refrigerate over-night, un-wrap and bake straight from the fridge in a pre-heated oven. If you let them rise past this time, the butter may melt out when the croissants are baked.
Place your oven rack on a the highest setting if your oven tends to brown more from the bottom-up, place the rack on a lower or middle shelf if it browns more from the top-down.
Bake the croissants for 21-25min or until golden brown.
Brush the leftover almond paste on top of the croissants and then press on slivered almonds and sprinkle with powdered sweetener. Enjoy your keto almond croissants!