Microwave a small bowl of butter. Mix in chopped pecans or pecan pieces and sprinkle with a pinch of garlic. Be careful not to add too much garlic or else it will end up tasting like garlic bread. Feel free to increase or decrease the amount of pecans. I have also substituted pecans for walnuts, but did not like the combination as much.
I always use a non-stick Panini maker. It involves less work than the pan, but do whatever makes you comfortable. Place two slices of bread next to each other on the grill. Begin with the slice on the right. Cover the slice entirely with the shredded Cheddar cheese. I prefer the shredded to the sliced, as it melts nicely in the grill. It's also a lot easier to apply.
Cover the right slice with a new slice of bread. Pour on the butter mixture. Now top the slice with the nutmeg, cinnamon and bacon bits. Add thin slices of fontina cheese to cover the mixture.
Finally, take the slice you originally had on the left and place it on top of the double slice you've been working on and press gently down on it. I prefer using three slices of bread total so the end result is not so flat and either overdone or underdone.
If you have chosen to use the Panini maker, press down on the sandwich, but be careful not to crush it. Your sandwich is complete when you can see light golden ridges on the top of the sandwich. If you are using the pan, lightly oil the pan. Allow the oil to heat on medium-high for some time before adding the sandwich and using a turner or whatever utensil you might have to press down on it. Flip the sandwich using the turner and make sure that the top has a nice golden tint. Do the same for the other side.