Extra Chocolate Chip Gluten Free Cookies

So, for an early valentines day present for my best friend, I decided to make Tanna some gluten free cookies! She loves chocolate, so one of the gluten free cookie recipes in my book included a lot of chocolate chips which would make it even more delicious! They looked delicious in the picture, so I decided to give this one a shot on my own.

The recipe was 

2/3 cup shortening

2/3 cup butter, softened

1 1/2 cups of sugar

1 1/2 cup of packed brown sugar

3 eggs

3 teaspoons vanilla extract

4 cups gluten free all purpose baking flour

1 1/2 teaspoon baking soda

1 1/2 teaspoon salt

3 cups of milk chocolate chips

The first step was to cream the shortening, butter, and sugar in a bowl until light and fluffy. Then beat in the eggs and vanilla, Then combine the flour, baking soda and salt and chocolate chips. Once it is thoroughly mixed, leave in the fridge for at least 1-2 hours (p. 282). 

After leaving the mixture in the fridge, the next step was to dump 1/4 cupfuls 2 inches apart onto the greased baking sheets, and bake at 375 degrees for 15-25 minutes. 

When they came out, I was sort of disappointed in the shape, and they were a little hard. But, my family absolutely adored them, so I'm hoping Tanna will too!

My question is why they came out so weirdly shaped and a little harder than I wanted them to be? Did I leave them in the fridge too long, or maybe the oven?