Before you start, note that due to the high-protein content, the crumb is slightly dryer than regular cake, and, you must add a frosting to enjoy it to the best. You can use the date frosting from the recipe, or my protein powder frosting (seen in pictures above),or simply serve with a dollop of yogurt.
Preheat the oven to 350°F (180°C). Line a 9-inch square baking pan with lightly oiled parchment paper. Set aside.
The day before, in a large bowl, add red split lentils, cover the lentils with cold tap water, and make sure you add a good 3 inches (10 cm) of water above the lentil level, as they absorb some during the night. Cover with a lid. Set aside overnight at room temperature.
The next day, drain red lentils in a sieve, rinse with cold water. Place in a blender jug, milk, yogurt, oil, and vanilla extract.
Blend on high speed until smooth, with no visible pieces of lentils remaining. Set aside.
In a large mixing bowl, add all the dry ingredients: flour, cocoa powder, sugar, baking soda, and baking powder. Whisk until well combined.
Bring back the jug with the blended lentils, and pour over the dry ingredients.
Use a rubber spatula to gently stir and combine everything together until smooth and consistent.
Pour the cake batter into the prepared pan.
Bake in the center rack of the oven for 30-35 minutes at 350°F (180°C) until a toothpick inserted in the center comes out with just a few crumbs on it, meaning the cake is baked, but still moist. Don't over-bake, or it will be very dry, due to the high amount of protein.
Let the cake cool down for 5 minutes in the pan at room temperature, then on a cooling rack for 3 hours, or until it reaches room temperature, before frosting.
In a saucepan, add chocolate chips, almond butter, almond milk, and pitted dates.
Bring to medium heat, and stir until the chocolate chips are melted. The dates won't dissolve, but the warm mixture softens the dates, and that's the goal of adding them to the pan now. It takes a few minutes to melt.
Remove from the heat, pour into a food processor, add the cocoa powder, and process on high speed.
Stop the food processor a few times, scrape down the bowl with a rubber spatula, and repeat until most of the dates are blended and turned into a smooth frosting - you will always have tiny bits of dates, and that's ok.
Spread over the cooled cake.
