WoWDB

Tigule and Foror's Strawberry Ice Cream can be purchased from various vendors including Alowicious Czervik in Orgrimmar and Emmithue Smails in Stormwind. These characters are up during Childrens week only- but are easily available for the achievement.

Red Velvet Cupcake can be purchased from Aimee in Dalaran (also in the Legion Dalaran under the same name.)

Lovely Cake Slice is actually created from using the Lovely Cake which should also be buyable from Aimee the cake can be used by your group- or you can just make multiple slices to do what you'd like with.

Dalaran Doughnut is sold by, you guessed it, Aimee

Dalaran Brownie is also sold by...do I really have to say it? Aimee

Delicious Chocolate Cake is made with cooking- the recipe, found here can be obtained from doing the daily cooking quests. Unfortunately, obtaining it is random from the cooking dailies, though the drop rates are likely higher than indicated since you cannot loot a duplicate once you get it.

Tasty Cupcake is also gotten from cooking. the recipe, located here is obtained randomly from Northrend mobs once you have a decent level in cooking. The recipe is actually quite common and can be found in dungeons.