I can't Google this out, everyone talks of pot brownies but these are just brownies made by a friend, diabetic and delicious and would love to bring a few with me on a trip. I am flying Vancouver-Los Angeles-London-Hungary-London-Coppenhagen-New York-Vancouver.
I think you went a little too detailed with trying to find your answer, the brownies are just like any other baked goods after all. I found this US government page saying:
Generally, there are no restrictions on baked goods. The U.S. Department of Agriculture's (USDA) Animal & Plant Health Inspection Service (APHIS) has a general list of approved products of which breads, cakes, cookies, and other bakery goods are listed.
The CBP Info center corroborates:
Make sure to check specific airline rules as well, but I doubt you'll have any issue bringing them.
As for the EU, Personal food, plant and animal product imports, this is the UK government website but its from EU Commission Regulation (EC) No 206/2009 which was transposed into UK law by: The Trade in Animals and Related Products Regulations 2011. To quote:
Confectionery, chocolate or cakes... are permitted from any country as long as they are for your personal consumption and do not contain fresh cream or high levels of dairy products.