If the dates are not very soft, cover them with hot water for 5 minutes, then drain and pat dry.
2. Place the oats in the bowl of the food processor and pulverize them until you have fine oat flour. Alternatively, you can use store-bought oat flour.
3. Add the pitted dates, tahini, maple syrup, vanilla, and salt to the oat flour. Pulse until the mixture forms into a sticky dough (it should turn into a ball). If it feels dry, add a spoon of plant-based milk a teaspoon at a time until the dough just sticks together when pressed.
4. Fold in 1/2 cup of the chocolate chips using a silicone spatula.
5. If the dough is too sticky to handle with your hands (this is more likely if your kitchen is warm), place the dough in the fridge for 20 minutes to firm it up a bit.
6. Line a 9×5-inch or 8×4-inch loaf pan with parchment paper, leaving some overhang. You can also use a similar-shaped glass storage container or an 8×8-inch square baking pan (if you use the latter, the bars won’t be as thick though). Spread the dough into the pan and smooth the top out evenly, pressing all the way into corners. Use a flat-bottomed glass to get the mixture evenly on top. Place the pan in the freezer for 30 minutes (or longer) to set.
7. Using the parchment paper as handles, lift the cookie dough out of the pan. Place the remaining 1/2 cup chocolate chips in a microwave-safe bowl with the coconut oil, if using. Microwave on high in 30-second intervals until the chocolate is almost melted. Use a spoon to stir the chocolate until it is melted. If you omit the oil, the instructions are the same.
8. Pour the melted chocolate on top of the cookie dough. Since the bars are cold, the chocolate will harden on top. Slice into 8 bars and serve immediately. Store leftovers in the freezer.