How to combine Mockito and Spring in TestNG

We are building an application which uses Spring Boot. We write unit tests using TestNG and Mockito. However I find it pretty annoying to write when(...) configuration, I would like to use real components instead. I started to use @Spy components instead of mocks and this works pretty well until I need to put a Spy into a Spy. I'd like to avoid loading a Spring Context if possible, because creation of the context is very slow it looks like overkill for me to load it for at max 5 classes.

Is there any way, how could I use real code instead of Mocks and not loading whole Spring context? Or is my approach wrong at all and I should mock out all other classes then the tested one?