Preheat oven to 350ºF. Combine almond flour, lupin flour, glucomann, monk fruit, and salt. Add in yolks, almond extract, and butter and mix until combined. Press into 9-inch tart pan (It will be just enough to provide a thin layer or a slightly thicker layer if you use an 8-inch tart pan). Prick all over with a fork. Line with well greased foil (buttered-side down). Fill with pie weights (rice works well) and bake at 350ºF for 15 minutes. Remove foil and bake another 8-10 minutes, until golden. Remove from oven and cool.
While the tart crust is cooking, prepare the filling. In small bowl, sprinkle gelatin over 2 tablespoons water to soften. Set aside.
Add the cranberries, allulose or stevia, salt, glucomann, and water to a medium pot and heat over medium-high heat, until the mixture simmers, stirring occasionally. Cover and cook for about 10 minutes, or until the berries are burst. Uncover and cook at a bare simmer for another 10 minutes, which will release the pectin and help with setting.
Remove pan from heat and use an immersion blender to puree until smooth. With blender running, add the egg yolks and softened gelatin and process until thick and smooth (the heat from the berries and pan will cook the yolks). Strain this mixture through a fine mesh strainer to remove the seeds and skins of the cranberries. Use a spatula or ladle to push the mixture through. It will be thick. Discard solids. Add in the butter and stir to combine until completely smooth. Taste and add more sweetener, if desired. Spread this mixture into the cooled tart crust and chill for 6 hours.
Before serving, beat cream with sweetener, salt, and vanilla until stiff peaks form, 3 to 5 minutes. Transfer to pastry bag fitted with piping tip and then pipe decorative whipped cream onto the surface of the tart. You can also keep the cream separate and serve with a dollop on top.