Preheat oven to 300°F. Line 2 baking sheets with parchment paper.
Prepare Binder ~ 10 minutes
Place prunes and water in a small pot. Simmer prunes on low heat on the stovetop until the prunes are plump and soft, about 10 minutes. No cook alternative: pour hot water over prunes in a heat-proof bowl. Cover with a kitchen towel or a plate. Allow prunes to sit in hot water to re-hydrate, about an hour, up to overnight. It does not have to be refrigerated while re-hydrating.
Place plumped prunes + 2 tablespoons of their water in a small blender or food processor. Pulse until a rough puree begins to form, stopping to scrape down sides with a spatula if needed. Add maple syrup and blend until a smooth puree forms.
Pour the maple-prune into the bottom of a large mixing bowl. Stir in olive oil, vanilla extract, sea salt, cocoa powder, and cinnamon if using, until well combined.
Bake Granola (40-50 minutes)
Add oats, nuts and seeds to the liquid ingredients in the mixing bowl. Using a spatula, stir to combine everything, making sure to scrape up the liquid ingredients from the bottom of the bowl.
Spread granola mix onto 2 parchment-lined baking sheets. Press down gently with a spatula to create an ever layer. Sprinkle with flaky sea salt. Bake for 20 minutes, then give one gentle stir for even baking. Bake for an additional 20-30 minutes until the granola is crisp. Total bake time will be 40-50 minutes.
Remove baking sheets from oven. If using dark chocolate chunks, sprinkle them directly onto hot granola so they melt slightly and adhere. Let Chocolate Granola cool completely on the sheets without touching it. I mean it. Completely. Do not touch it.
Once cool, add chopped prunes and dark chocolate chunks if using.
Store granola in an airtight container on the countertop for up to 1 week or in the refrigerator for 2-3 weeks. Nutrition information is an estimate and based on one (1) ½ cup serving without optional dark chocolate chips. If you add the chocolate chips, calories per ser serving increase by ~ 20 calories.