How do you emphasize the yeast flavor in bread?
Use lots of yeast, and short fermentation times. Prefer cake yeast over the dried types. 

Fresh yeast has a specific taste and aroma, which disappears during fermentation, giving you a different, bready taste, which is not the same as yeast taste. Pro bakers are normally trying to achieve perfect fermentation, using low yeast amounts and long fermentation types. Household recipes are trying to take a more convenient route, preferring speedy fermentation (so baking times are reduced) and lots of yeast (because 1. this allows for even quicker rising, and 2. some decades ago, yeast quality was not so good, and you had a chance that the culture in a cake you purchased was barely alive, so it wouldn't rise if you used the minimal amount pro bakers with fresh daily supplies went for). This results in lots of unfermented yeast, which gives homemade breads a specific yeasty taste. While pro bakers will try to avoid it, many people associate the taste with pleasant experience of homemade bread made by a beloved family member, and like having it in their own bread. 

So, use cake yeast. About the highest amount you can get away with would be 10% (50 g cake yeast per 500 g flour). But if your bread starts getting a whiff of ammonia, reduce it a bit. Ferment at warm temperatures (30°C is good, yeast starts slowing down over 35) and wait for volume doubling at each stage - should take 30-40 minutes per stage. Be careful to not overproof, because with this ammount of yeast, the dough is fickle, and may not rise if proofed for too long.