Can I cast a Magic Initiate spell using my own spell slots if the spell is also in my class spell list?

Question

yes, I know, this question is very similar to others I've found.

Can you cast a magic initiate spell using spell slots?

The above post concludes that if the caster does not choose their own class, they cannot cast the spell learned through the feat Magic Initiate.

My question is this: if the spell learned through Magic Initiate exists in my spell list, but I chose another class for some reason, can I still not cast it using my own spell slots?

For example, let's say I have a wizard and decided to take the Magic Initiate feat, and chose to take the spell from the bard class. The spell of choice: Tasha's Hideous Laughter (or Hideous Laughter).

Since this spell is both on the bard and wizard's spell list, could I use my own spell slots to cast it?

Answer 1

No.

As the linked question and answer indicate, your Wizard Spellcasting feature specifies you can use those slots to cast Wizard spells. You can't use them to cast Bard spells. Even if you were a multiclass Wizard/Cleric using the optional multiclassing rules, those rules say you can use those slots to cast any spell in a class that gives you the Spellcasting feature, and because you're not a Bard, you still cannot cast Bard spells in those spell slots.

If you were a multiclass Bard/Wizard, though, you could cast your Bard spells (from Magic Initiate or your Bard levels, either one) in your multiclass spell slots.

(Note that you could simply choose Wizard for your Magic Initiate feat and take Hideous Laughter as a Wizard spell, and be able to prepare it normally. I'm assuming you're trying to get a specific Bard cantrip and that's why you want the feat to grant Bard spells, but then you'll only get the 1/day from Magic Initiate, and of course cast with your CHA instead of INT.)