Spray a 9 X 13-inch pan with butter-flavored cooking spray. Spread the rhubarb and the strawberries in the bottom. Sprinkle the fruit with cinnamon and with one-half cup of the sugar. You'll notice I didn't put an amount for the cinnamon or nutmeg. You get to choose the amount based on your taste. If you've ever made cinnamon toast, you'll know how much cinnamon I put on. It's a dusting.
In another bowl combine the eggs, the salt, the rest of the sugar, and the flour. Use a pastry blender or a fork to get it all mixed up. It will be slightly lumpy and crumbly. Don't worry. Just get it mixed well so the flavors mix and the eggs get distributed.
Pour the mixture over the fruit and spread it from end to end. Some of the fruit might be sticking up through the flour mixture. That's fine. Drizzle the melted butter over the whole thing. It won?t cover every bit. That's fine too. Then sprinkle on the dusting of nutmeg.
Pop it in the oven at 350 degrees for 40 to 45 minutes. Watch for a lightly browned crust to appear -- very light brown. As the crisp cools, the topping becomes crusty. That's why they call it "crisp." By the way, I don't cover crisp to store it. If there's any left overnight, I only cover the edge where it was cut because if you cover the crust, it will go from crispy to soggy. It's okay that way; it's just not "crisp." More often than not there won't be leftovers to even concern yourself with.