Back in August of last year, I told you about a new treat shop landing in the old Blue Plate space at 1415 Montana Ave.  You wouldn’t know it from the lack of signs, but Santa Monica’s branch of Erin McKenna’s Bakery opened over the weekend, joining locations in New York, Orlando, and on Larchmont.  Look for a menu of donuts, muffins, cakes, and other sweets, as well as breakfast and lunch items that are vegan, gluten-free, refined sugar-free, and kosher.