Line an 8x8 baking dish with parchment paper.
To toast nuts, preheat oven to 350 degrees. Place the almonds, pecans, walnuts, and pepitas on a cookie sheet and toast in oven for 5-8 minutes, careful not to burn.
Set toasted nuts aside and allow to cool. In a small saucepan, combine almond butter and maple syrup on low heat. Once thoroughly combined, add vanilla extract and pinch of salt. Place nuts in a large bowl, add chia seeds and almond butter mixture. Stir until nut mixture is evenly coated.
Transfer mixture to the lined baking dish, and using a piece of parchment paper or plastic wrap, press mixture into baking dish until packed.
Place baking dish in fridge for at least 30 minutes before removing from dish and cutting into bars.
Once the bars are chilled and firm, melt the chocolate in a double boiler or metal bowl placed over a saucepan that has a few inches of simmering water (careful to not allow water to touch bowl). Use a rubber spatula to stir and scrape sides of bowl. When the chocolate has melted, whisk in vanilla extract, maple syrup, and salt. Once combined, remove from heat.
Dip one side of each granola bar into chocolate and place on a piece of parchment paper to harden.
Keep bars in an airtight container in the fridge or freezer.