Jockey Paul Townend rode the Willie Mullins-trained Penhill sweetly throughout and after winging the final flight, he kept on tenaciously to master Jessica Harrington's Supasundae (6/1) and score by two lengths. Nigel Twiston-Davies' Wholestone (14/1) stayed on well to finish a further three lengths behind in third.
Bloom, who will hope to see Albion cause a FA Cup shock when they travel to Manchester United on Saturday, said: "To go there and win outside of novice company for the first time is unbelievable and it was brilliant ride by Paul.
"Back in the summer, we were worried as to whether he would run again, but a few months back, I was told he was getting better and fit, but to be able to come back from all that time out and win a Grade One championship race was brilliant.
"He has done it with absolute style. I was concerned two hurdles out whether he would get up the hill after such a long time out, but he has won it going away.
"Paul did brilliantly, he gave him a quiet ride and then coming down the hill, we started to get confident and then jumping the last and going clear was a brilliant effort.
"We had a bet on him, more with hope that expectation but it was a good price and another winner."
Mullins, registering his sixth winner of the week and his 60th success at The Festival overall, drawing him level with Nicky Henderson as The Festival's winning-most trainer, said: "Penhill must have some engine. I could not believe it watching Paul come down the outside and I thought wow - if he fluffs the last then he could blow up and fall in a hole, but he met the last perfectly and then I thought Supasundae would out gallop him but he kept on powerfully. It is fantastic for Tony Bloom."