100% certainty : Marius & Fanny on Samson. A bit expensive but good cakes are unless you have crisco for the butter cream.
Other good choices:
-Ambrosia Bakery on Samson
-Pagel in Marche 440 (but i heard they were bought by Gascogne? which is also good)
-Adonis for a pickup cake. On cure Labelle or try the bigger one on Thimens in VSL.
I strongly suggest les delices lafrenaie. They have excellent cakes and were happy to take a request to add an edible cake image that I brought over for a child's birthday. Depending how many people you are, you might want to get a few smaller cakes (in the 35$ range). If you go to chenoys on cure labelle in chomedey you can order these cakes instead of going to St Leonard. They have out of this world oreo, skor, and Ferrero rocher cakes, as well as classic apple pies and cheese cakes.
You can also try and order directly from the bakery and ask them to deliver to Chenoys in Laval, which I have done for the cakes already in stock, but I have not yet tried for the ones available only there.
On my daughters first birthday I ordered a dealth by chocolate and a strawberry short cake...the contrast in flavours was appreciated by all the guests!
P.s For the smaller cakes in the 35$ range you only need to order them a day or so in advance :o)