Line your baking dish with parchment paper or grease it with margarine or cooking spray.
Add all your ingredients in the food processor and process until the mixture comes together.
Transfer the mixture on your prepared baking dish. Push down the mixture with a spoon and smooth out the surface. The mixture will be sticky.
If you want to add the oats on the top of your mixture spread it out evenly on the surface and press them down a bit.
Now put the baking dish in a freezer for about 1 hour so the mixture can firm up.
Using a sharp knife you should be able to cut the bars. If you left the bars in the freezer for a bit longer wait a few minutes and then cut the oat bars.
Notes
You can keep the oat bars for about a week in the fridge or freeze them for later.