There are countless places where you can have breakfast at El Paujil. My favorite in Café La Sonora.
La Sonora is located on Carrera 4, at the corner with Calle 5. They have amazing coffee that comes from local farms. Their espresso machine is an Italian one. This makes their espresso one of the best I have tried while traveling abroad.
As far as food options, they have various homemade cakes.
Their prices are very reasonable, with an espresso being sold at roughly $0.75.
You can learn more about Café La Sonora by visiting their instagram profile.