As others have said, getting to Kouzzina from Epcot is really easy. Exit Epcot via International Gateway (located between UK and France). It's about 0.35 miles from IG to the Boardwalk. When you reach the big split in the path, take the bridge that goes over the canal. (There is a small split in the path that let you walk along the canal, but this won't get you to the Boardwalk. Just stay to the right initially and you'll be fine.)
There is also the boat that goes from Epcot to BW to YC/BC to S/D to DHS. BW is the first stop after Epcot, so it's a pretty short ride. After a long day of walking at Epcot, my family usually opts for the boat.
As others have mentioned, there are buses directly from resort-to-resort. After dinner, if Epcot is still open, you can head back into the park and then catch your bus out front. If DHS is open late, that is another option.
You can also take a bus to DTD (not necessarily the most time efficient option). The Epcot area resorts usually all share a bus, so it may have already stopped at YC, BC, Swan, and/or Dolphin before getting to BW. Just keep that in mind if you don't like crowded buses. Luckily, you'll be heading to DTD and not trying to get back to the BW from DTD.
Another option is to take a taxi back to your resort. There are usually several waiting out front of the BW. It runs between $15 and $20 plus tip to get anywhere on property.