To add, you are "notching" a groove into the stone to insert the counter thickness. It appears the stone is a thinner flagstone, not fully 12" thick, if so cutting into it would be much easier.

Thank you for the advice! My husband suggested that but I was skeptical. I was considering a solid surface countertop that could be scribed against the wall but I really love the look of natural stone.

With a backsplash we were thinking of just filling in the top gap with mortar?

The stone is pretty much a backsplash. I'd also scribe the counter and caulk with a color matched to the counter flexible caulk..I wouldn't cut the stone.

You could do butcher block with those stone walls and scribed perfectly .I would not touch that stone . This wall needed trim at the floor and we just scribed it to fit the wall it worked great since it alon had to be done in the LR around the FP base Then I just color matched the stone for paint Wood is easier to scribe for sure.

Thank you! My husband had mentioned butcher block as well!

I too would not touch the stone walls. Your walls will be around a lot longer than the kitchen you are putting in. Think of the countertop as temporary and the walls as permanent.

Butcher block would look great. My friends live in an old house that was a hospital during the civil war. The kitchen is in the basement with very thick stone walls. They scribed butcher block countertops.

Thank you!