In a large mixing bowl, combine the rolled oats, chopped nuts, chia or flaxseeds, along with cinnamon if using. Stir well until everything is evenly distributed. Set aside.

In a medium saucepan, add honey or maple syrup and nut butter. Place over medium heat, stirring for about 3-5 minutes until the nut butter melts and blends with the sweetener. Add vanilla extract if desired, then remove from heat once smooth.

Pour the warm wet mixture over the dry ingredients. Stir to ensure every oat and nut is coated, binding the bars together.

Line an 8x8 inch baking pan with parchment paper. Transfer the granola mixture into the pan, spread evenly, and press down firmly to compress.

Chill in the refrigerator for at least 2 hours or in the freezer for 30 minutes to set properly.

After chilling, lift the mixture out of the pan and cut into bars or squares. Store in an airtight container at room temperature for a week or refrigerate for freshness.