What if you went to your manager, or whoever you feel is the right person, asked if you could speak one on one, and said...
"I really love working at this company. The work is interesting, I love the people, the culture, <one more legitimate pro goes here>. But I also know I could be making X if I went elsewhere. I love the work I'm doing, and I want to keep doing it here, but I also don't want to be leaving money on the table. What can we do?"
This phrasing, pretty much verbatim, has worked really well for me in the past.
"I really love working at this company. The work is interesting, I love the people, the culture, <one more legitimate pro goes here>. But I also know I could be making X if I went elsewhere. I love the work I'm doing, and I want to keep doing it here, but I also don't want to be leaving money on the table. What can we do?"
This phrasing, pretty much verbatim, has worked really well for me in the past.