The 33-year-old music teacher failed to make the quarter final after his Showstopper layered custard gateau collapsed, but 82-year-old judge Leith said his honey, bay leaf and thyme custard would "stay with me for the rest of my life".
Kevin burst into tears as he confessed: "I'm nothing but proud. Imposter syndrome is real, and coming into this competition I didn't feel like I deserved a place.
"I feel like I can count myself as one of this talented bunch."
Leith said: "I will be sad to see Kevin go but that custard will stay with me for the rest of my life. I'm going to go home and do it."
The Scottish teacher served his honey, nectarine and raspberry custard gateau to the judges on two plates, covered with a mound of fruit and macarons, after he admitted it was not stable enough to support all three layers.
Judge Paul Hollywood said: "Have we had an earthquake? It's literally just been dropped... It is delicious, it's a shame that it looks a mess."
Leith said: "That custard is amazing, it's so unusual. The more you have it in you mouth the nicer it is."
Head teacher's PA Janusz, 34, narrowly avoided being sent home after his custard was deemed "too gloopy".
Hollywood said: "The custard's more like wallpaper paste."
Cardiovascular research assistant Syabira, 32, was declared Star Baker for the second week in the row after serving up a spectacular pina colada flavoured gateau with edible floral decorations.
Leith and Hollywood both agreed she had achieved the perfect balance of custard that was thick enough to support the cake without being gloopy.
Syabira said: "I feel like did I really make that? I'm standing there but I want to drop down to the floor because it's too much to handle."
She added: "I wouldn't have imagined I would get a Star Baker second in a row, that is wild."
Nanny Sandro, 30, admitted he was disappointed not to win the title for his layered cake flavoured with coconut and mango, demonstrating impressive pipework for decoration and in tribute to his late friend.
Watch: Former Great British Bake Off contestants reveal who they are tipping to win this year