Base: Place pecans in a food processor (or high speed blender) and process until the pecans become small and crumbly. Add dates and porridge oats to the pecans and process again until the mixture sticks together and the dates are well processed. (If you are not using a high speed blender you may need to transfer mixture to a bowl and hand mix in the remaining ingredients). Add the remaining ingredients and process again until the mixture turns a dark chocolaty brown. Stop processing before it gets to buttery. Put the mixture into an 8″x8″ baking pan and press down firmly with your hands.
Icing: Place all ingredients in a high speed blender. Let them sit for about 2-3 minutes to soften the dates. Blend, starting at a low speed and gradually increase the speed. Keep blending until it is velvety in texture. (You may need to stop once or twice and scrape down the sides). Spread icing over the brownie base and refrigerate a minimum of 2 hours before serving.