Start by preheating your oven to 350*F.

Wash and chop off the tops and ends of your rhubarb (like you would with celery), cutting the rest of the stalks into 1/2" inch pieces. Wash and pat raspberries dry and set aside with rhubarb for later. You can also cut these in half if you'd like but they'll break down on their own pretty well in the batter.

In a large mixing bowl or stand mixer, beat together the eggs, oil, and milk until well combined.

Measure out your dry ingredients for the batter and add to the wet mixture, stirring until everything is well blended and no dry pockets of flour or anything is left, about 3-5 mins on a low stirring speed. You may need to scrape the bottom of the bowl with a spatula periodically to make sure there aren't any stuck bits at the bottom.

Fold in the rhubarb and raspberries with a spoon or spatula, making sure they get coated in the batter well but trying also not to overmix it.

Pour batter into a 9"x13"x2" pan, greased with butter or Pam spray.

Next, make the topping. You may need to put the butter into the microwave for about 30 seconds to make it more malleable with the flour, cinnamon, and brown sugar. It's easier to use your hands to mix this part by kneading until it resembles the texture and shade of wet sand. Sprinkle evenly over the batter and bake in the oven for 50 minutes, or until an inserted knife or toothpick comes out cleanly with minimal crumbs.

Cut into squares once cooled and enjoy! This will last in the fridge in a Tupperware container or ziplock bag for up to two weeks.