Easy Cookie Bars from Cake Mix

This is how to make cookie bars with cake mix, M&Ms, chocolate chips and oats baked in a 9×13 pan or round pan to make an easy cookie cake. You are going to love this boxed cake mix hack for dessert tonight.

Our easy cake mix bar cookies are the bomb. It is a bit of a cheater way to bake “homemade” when guests come over. If you have ever had a cowboy cookie these are kinda’ similar. Meaning you add ALL the add ins you want so there are surprises with every bite.

The only really big difference between these and cake mix crinkle cookies is that you slice them and there are more add-ins. They are a bit more tender too since you don’t get the crisp outer edges on each one. Especially the center pieces won’t have any of that. Either that is a huge plus to you or if not then you might prefer cookies.

I guess I would say they are a cross between those and our cake mix brownies. Yes, if you can tell I am all about tweaking a boxed mix into something else entirely. Not to say that we don’t bake it as directed on the back every once and a while, but more than half the time we don’t. 😉

Easy Monster Cookie Bars Ingredients

Brown sugar will add more sweetness, just like homemade batter would need but we are making a cheater way this time. 😉

What kind of cake mix makes the best bars?

I like to start out with a box yellow cake mix (what we used here), or white. In this case it is best to use one that has the mildest flavor so the add ins really shine thru with those flavors instead of being overcome with the flavor in the mix.

You want to add creamy salted Butter at room temperature in order to cream everything together in a bowl.

I think that adding smooth peanut butter is best, or any nut butter works if there are allergies in the house. For something like sunflower butter with oil on the top make sure to stir well so it is nice and thick.

You will want to add a large egg or egg substitute product to add a bit more moisture to make the dough thicker, it will be a bit sticky but firm enough to pick up.

I like to add some quick oats (not old fashioned) which will add some texture and fiber as well into this dessert.

I like to add semi sweet mini chocolate chips or peanut butter chips to make chocolate chip cookie bars

Adding some small candies or chocolates like m&ms are great

You will need a few tbsps of water, vegetable oil or really any liquid will work with this, even Sprite. Large bowl and rubber spatula to mix ingredients with a baking sheet. You can use a piece of parchment paper on the bottom or spray with cooking spray so they don’t stick. I like to only bake one cookie sheet at a time so they all come out with the same consistency.

Variations

Just like lemon bars with cake mix, you can really add what you love. If you’d prefer Reeses pieces to chocolate pieces then by all means use those. I would stick to our measurements and not omit the oats because that helps with the texture and keeping them together.

Just tweak the add ins if you use a flavored mix like chocolate cake or something. I think all of these would work well with that but for lemon I might use white chips, no peanut butter but maybe nuts would work better for that instead. Chocolate chunks are great in the Fall with our pumpkin bars with cake mix variation on this idea.

You can jump to recipe below and preheat your oven to get started on your cake mix cookie bar recipe but I suggest reading the tips below so they come out perfect.

How Long to Bake Cookie Bars with Cake Mix

You want to make sure you keep these moist, so check at the minimum bake time of 25 minutes in the center. Use a toothpick, you want it to come out mostly clean but with moist crumbs attached. If there is wet batter bake a few more minutes up to 30 minutes until top is golden brown and cracking a bit.

It is important to take note of the total cook time and stay close near the end. You do not want to bake this too long or it will dry out. I would rather have it a bit underdone than over. AND remember that when they are left in the pan when taken out they will continue to stiffen up with the heat of the pan.

Can you make this into a cookie cake?

Yes, if you wanted to bake this in a 9″ round pan it would be thicker so you would likely need 35 minutes to bake all the way thru. This is a fun and different birthday idea you can slice like a pizza with a pizza cutter into triangles and serve with a squeeze of frosting on top with a candle.

How do you know when cookie bars are done?

This is KEY when you are baking this or a pan full of cherry brownies. The texture is everything!! Set for the minimum bake time listed and then turn on the light. What you want is the outside edges to start cracking and firming up and the middle to be tender but not wet. If it looks like it is close use a toothpick.

Insert into the center and if it is still wet and liquidy, give it 5 more minutes and check again. However when you pull it out if it is clean but with very moist crumbs attached, pull it out. Do NOT slice it yet though.

Set it on a cooling rack until it is at room temperature. That gives it time to continue baking in the pan. Then it is will be perfect!! Want another treat? Try our lunch lady peanut butter bars with these! Use the same size pan and cut into squares without any need for baking with this one so you can make the night before.