Preheat the oven to 350°F, and position the oven rack to the center position. Line an 8x8 baking pan with parchment paper.
In a mixing bowl, mix together 2 & ¼ cups of rolled oats, ⅓ cup of cocoa powder, 1 teaspoon of salt, and 1 teaspoon of baking powder until well combined. Set aside.
In a separate bowl, combine 1 & ¼ cups of milk, 3 tablespoons of melted and cooled coconut oil, ⅓ cup honey, 2 eggs, and 1 tablespoon of vanilla extract. Whisk to combine until completely incorporated.
Add the wet ingredients to the dry ingredients, using a rubber spatula to fold the ingredients together. Then, fold in ½ cup of chocolate chips and ⅛ cup of chocolate chunks, reserving some for the top and for the chocolate drizzle.
Pour the mixture into the prepared baking pan, and top with an additional ¼ cup of chocolate chips, and another ⅛ cup of chocolate chunks. Bake for 30-35 minutes until the center of the oats are set in the center. Allow to cool in the pan for 10-15 minutes before cutting them into 9-12 pieces.
Meanwhile, place the remaining chocolate chunks in a microwave safe bowl with the remaining 1.5 teaspoons of coconut oil. Microwave at 50% power in 15-second increments, stirring in between to melt until smooth.
Drizzle the cut bars with the optional chocolate drizzle, then top with flaky sea salt and optional berries. Enjoy!
Store leftovers in an airtight container in the fridge for up to 4 days. Reheat gently in the oven or in the microwave.