Preheat the oven to 375 degrees. In a large bowl, whisk together the yogurt, eggs, brown sugar, vanilla, cinnamon, baking powder, and salt. Once the mixture is whisked smooth, add the milk and whisk until smooth again.
Roughly chop the walnuts and dates until they are in small pieces. Add the walnuts, dates, and rolled oats to the milk mixture. Stir until well combined.
Pour the oat mixture into a 8x8 or 9x9 inch casserole dish coated with non-stick spray. Bake in the preheated oven for 45 minutes, or until the center is no longer wet.