Hearthpwn

Overview:
Use the upgraded power from Baku the Mooneater to armor up and outlast her until she top decks.

Mulligan:
Mulligan for the 1-Drops and another early-mid card (Brawl, Rabid Worgen, Fierce Monkey)

Early Game:
Try to keep up with her as much as possible and spend as many cards as you can each turn. Her hero power can cause big problems, but the upgraded armor will be able to soak up a lot of the damage. Warbot and Eternium Rover benefit from the trickling 1 damage of her hero power and if she drops a bigger minion, you can use hero power and Shield Slam for 4 damage.

Mid Game:
Fierce Monkey, Rabid Worgen, Zilliax, Psych-o-Tron and Clockwork Goblin will help mitigate the damage as she'll be nearing top decking.

Late Game:
She'll still be able to drop minions and you might be trading with her, but you'll reach a point, where she will no longer be able to threaten you because of the large armor from the hero power and Dr. Boom, Mad Genius. Dyn-o-matic is great as single minion removal, rather than a wide board, and SN1P-SN4P, Wargear and the Frothing Berserkers will help finish her.

Video:

My other Curse of Naxxramas decks:
Arachnid Quarter
     Anub'Rekhan (Taunt Warrior)
     Grand Widow Faerlina (Odd Warrior)
     Maexxna (Dragon Priest)

Plague Quarter
     Noth the Plaguebringer (Spell Hunter)
     Heigan the Unclean (Control Shaman)
     Loatheb (Control Priest)

Military Quarter
     Instructor Razuvious (Taunt Druid)
     Gothik the Harvester (Mill Druid)
     The Four Horsemen (Resurrect Priest)

Construct Quarter
     Patchwerk (Freeze Mage)
     Grobbulus (Odd Patron Warrior)
     Gluth (Divine Shield Paladin)
     Thaddius (Control Warlock)

Frostwyrm Lair
     Sapphiron (Fatigue Mage)
     Kel'Thuzad (Mill Rogue)