Preheat oven to 350°F (180°C) and line a baking pan with parchment paper.
Soak & blend dates. Place the dates in a bowl and cover with very hot water. Let soak for 10-15 minutes to soften. Then drain and transfer the soaked dates and soy milk to a blender. Blend until you have a smooth paste (use a tamper if needed). See notes for blender tips.
10.5 ounces (Medjool) dates (around 2 cups), 1 cup unsweetened soy milk
Mix dry ingredients. In a large bowl, whisk together flour, almond flour, cocoa powder, baking powder, and baking soda.
1 ¾ cups white all-purpose flour , 1 cup almond flour , ⅓ cup unsweetened cocoa powder , 2 teaspoon baking powder, ½ teaspoon baking soda
Add wet ingredients. Stir in the oil, yogurt, and the date-soy milk mixture from the blender. Use a spatula to gently mix until just combined.
½ cup rapeseed oil, ¼ cup unsweetened (Greek) yogurt
Optional add-in: If using, fold in the chocolate chips.
⅓ cup dark chocolate chips (optional)
Bake. Pour the batter into the prepared cake pan and bake on the center rack for about 30-35 minutes, or until a toothpick comes out clean. Let the cake sit in the tin for 10 minutes, then carefully transfer to a wire rack to cool completely before adding the ganache.