Preheat oven to 350 degrees Fahrenheit. On a baking sheet, spread almonds, pistachios, and cashews and toast in oven for about 5 minutes. Watch carefully so they don't burn. Pistachios seem to toast up quicker than the other nuts.
Set toasted nuts aside and allow to cool. In a small saucepan, combine almond butter and maple syrup on low heat. Once thoroughly combined, whisk in vanilla extract and sea salt. Place nuts in a large bowl, add hemp hearts and almond butter mixture. Stir until nut mixture is evenly coated.
Line two baking sheets with parchment paper. Spray your hands with cooking spray, and using a small spoon scoop nut and seed mixture and form a ball with your hands. Place on baking sheet. Spray your hands with cooking spray intermittently so that mixture does not stick to hands. Repeat until entire mixture has been formed into balls. Sprinkle additional sea salt over each bite. Place baking sheets in refrigerator for at least 30 minutes or until bites have firmed up.
Once the bites have chilled, place the chopped chocolate in a glass or microwave safe bowl and microwave for 30 second intervals, stirring after each interval. When chocolate has melted, whisk in vanilla extract, maple syrup, and salt. Working quickly while chocolate is melted, dip the bottoms of the bites in the chocolate and place them back on the baking sheet with parchment. I find using a small spoon to scoop up the melted chocolate and place the bottoms of the bites on the spoon works best.
Place baking sheets back in the refrigerator until chocolate has hardened. Transfer to an airtight container to store.