Omelet
I got a new lunch box, so I cooked rolled omelet.
I added too much sugar by mistake. The omelet became too sweet.
Oops! (T_T)
I got a new lunch box, so I cooked a rolled omelet.
By mistake, I added too much sugar and the omelet became too sweet.
NOTES:
1. "cooked" is acceptable, "made" (to make) can be used too.
2. some a were missing
3. This can be used at the beginning or ending, you can also use 'because I added too [...]', see ***
4. Combine the sentences. (Think like in Japanese: [...] から、[...]。)
5. 'became' is acceptable, using 'was' is better.
*** Alternative sentence: Because I added too much sugar, the omelet became too sweet.