Mt Leinster, the 1/2 favourite, set out to make all but gave Sean O'Keeffe some very worrying moments through sketchy jumps.
Kapard was ridden to get the better of the leader after that obstacle and looked to have sealed the race as she asserted coming to the last.
However, Mt Leinster got a second wind and reeled her in to jump the last with a fractional advantage.
On the run-in, Mt Leinster found generously to take over again and was driven out to see her rival off by half a length at 5/2.
“It was a small field but there was plenty happening,” said Blackmore.
“It was a great performance by her and hopefully she's going to do a lot more now over fences than she did over hurdles. It's a great starting point for her (over fences).
“I thought turning in I still had plenty under me. She picked up the whole way up the straight, idled a bit when I got to the front but then battled back really well again.”
Reflecting on yesterday with A Plus Tard in the Betfair Chase at Haydock, she added: “It was incredible. It was such an enjoyable race to ride, he was just in top form yesterday and put up a performance to match that.
“It was a brilliant crowd over there and it's definitely a track I like going to now.”