Originally Posted by
MCPE
From my experience if you want to complete the goal you'll need 4 Oven from the first goal and 7 Oven from the second goal, I know that'll take so many parts. So Instead of spending gems on oven parts, I have a little trick that I always use to get extra oven Parts but this will cost you quite a lot of coins depending on how many parts you need and your luck as well.
What I did is, I cook a goal recipe to get the collectibles that you can trade for a goal parts and then I just reset the recipe and do it over and over again till I have enough. It's a very tedious process, But it works.