Preheat oven to 350°F. Lightly grease a 9 x 13 inch baking pan (I use coconut oil to do this.) You can also use 2 8x8's with not much difference in the end result.
Place the flour, sunflower seeds, and gelatin in the bowl of a food processor and process until the seeds are finely chopped.
Add the coconut oil and sweetener and pulse until the mixture is crumbly meal, similar to a pie crust. Be careful not to over-process.
Press the mixture into the prepared baking pan(s).
Bake for 8 – 10 minutes, until crust is lightly browned.
While the crust is baking, start preparing the filling.
Put the eggs (or egg substitute) in the food processor and pulse until the yolks are broken. Add sweeteners, arrowroot (or cornstarch) lemon zest and juice, and milk. Pulse several times until combined.
When the crust is finished, pour the lemon mixture over the crust (no need to wait for it to cool).
Sprinkle shredded coconut or sweetener evenly over the top of the bars.
Bake 15–20 minutes, until the filling is set. Cool completely. Cut and serve. Store in the refrigerator (especially the ones with eggs in them :-))
For a vegan filling, substitute in agar powder for the gelatin powder.