Crust: Preheat oven to 350°F. Line 8-inch square baking pan with parchment paper. Allow parchment paper to hang over the edges of the pan. This will allow for easy unmolding. Set aside.
In a medium bowl, mix together almond flour, almond butter, ground flax meal, sugar, salt, and water until dough forms. Use a spatula or use gloved hands to bring dough together.
Transfer dough to prepared baking pan. Use a tamper or the flat bottom of a measuring cup or drinking glass to press dough into an even layer. Bake for 15 minutes. Set aside.
Filling: Peel sweet potatoes. Cut into 1 1/2-inch chunks. Place sweet potatoes in sauce pot. Cover with water and bring to a boil. Reduce to a simmer and cook for about 15 minutes, until sweet potato is tender. Drain well. Add sweet potatoes to a blender.
Pour coconut milk, agar powder, and agave nectar in a small sauce pot. Stir contents often. Simmer until agar has dissolved.
Add agar mixture, vanilla extract, and salt to blender with sweet potatoes. Process mixture until thick and smooth.
Pour sweet potato puree mixture on top of baked crust. Spread filling into an even layer. Let mixture cool for about 20 minutes before transferring to the refrigerator. Chill for at least 4 hours until filling is set.
Use a sharp clean knife to slice sweet potato pie into desired bar sizes.