Review the original item:
Ingie looked at his wife's collection of cookbooks and
sighed,
although there were thousands of recipes for delicious meals, he
knew that Valerie would want to order another pepperoni and mushroom pizza
for dinner.
You wanted to fix it this way:
Ingie looked at his wife's collection of cookbooks and
sighed;
Although there were thousands of recipes for delicious meals, he
knew that Valerie would want to order another pepperoni and mushroom pizza
for dinner.
A semicolon is an excellent way to join two complete sentences. You must, however, use the semicolon correctly.
Do not capitalize the word that follows the semicolon unless it is a proper noun, one that is always capitalized.
You might want to consult the rules for fixing comma splices and fused sentences.