I was all excited when we first looked at this house and saw the newly remodeled kitchen. And granite tile!
What I didn't understand is that granite tile is different than one whole piece of granite. As soon as I began baking, the flour got onto the granite tile. Mostly, it got into the grout. If it got wet, it turned the brown grout white. After paying over $500 to have a professional company clean up the grout and seal it, I decided to change things. I had used a baking sheet, but I guess it wasn't large enough. I added sheets under the baking sheet sometimes. Things slipped. I added cutting boards and silicone baking sheets. around the baking sheet, but flour got through the cracks where they met. I tried really hard to keep any flour from getting onto the tile and getting wet--then I would brush the dry flour away with a whisk broom. That worked, but I was nervous the flour would get wet.
Finally, I decided to see if I could make myself a large "cover" for my kitchen island out of plexiglass. Then I could put my baking sheet on top of that! I have used plexiglass before for temporary holiday baking, and it kept my counters neat. This sounded like a good plan. I shared it with some of my baking buddies, and got some ideas on how to keep the plexiglass in place.
I checked out Lowes and Ace Hardware ( I had purchased plexiglass from them before). All of the pieces were no longer than 48". My island counter is 51". Ace suggested that I try the local glass company. The local glass company could cut me the right size, but it was $60! I decided to go back to Ace Hardware. Those smiling guys cut the piece cut to size and I had an extra piece to boot, all for under $40!
Here's a picture of it on my counter. It's 3" short, but that's ok. And I don't have to worry about how to round the corners. It's covered with a film of plastic right now. If I want, I could remove the plastic and just use the plexiglass as a wonderfully large baking sheet!
I've just begun using this piece, and I just LOVE it! Maybe this solution can help you?