Aberrant Dragonmark Feat Question

[ATHATH]

You learn a cantrip of your choice from the sorcerer spell list. In addition, choose a 1st-level spell from the sorcerer spell list. You learn that spell and can cast it through your mark. Once you cast it, you must finish a short or long rest before you can cast it again through the mark. Constitution is your spellcasting ability for these spells.
Can a spellcaster expend spell slots to cast their 1st level Aberrant Dragonmark spell with CON as their casting stat more than once per short rest? Does the answer change if that AD spell is on their spell list? It seems to me like the 1/short rest limitation is for the free castings from the mark, not for casting it normally if you learned it via the mark.

[Dualight]

Considering that other feats (such as Fey Touched) explicitly call out that you can, but Aberrant Dragonmark does not, it is safe to conclude that casting the Dragonmark spell through the dragonmark (so using CON) cannot be done with a spell slot, only with the feat. Knowing the spell from another source (that does allow slot-based casting) would allow you to cast that spell more often than the Aberrant Dragonmark feat alone, but you would be casting it through that other feature, so it would use the spellcasting ability of the non-dragonmark source, not CON.

All that said, you might be able to talk your DM into allowing spell slots, but RAW you cannot use slots for the CON-based casting.

[Khrysaes]

Considering that other feats (such as Fey Touched) explicitly call out that you can, but Aberrant Dragonmark does not, it is safe to conclude that casting the Dragonmark spell through the dragonmark (so using CON) cannot be done with a spell slot, only with the feat. Knowing the spell from another source (that does allow slot-based casting) would allow you to cast that spell more often than the Aberrant Dragonmark feat alone, but you would be casting it through that other feature, so it would use the spellcasting ability of the non-dragonmark source, not CON.

All that said, you might be able to talk your DM into allowing spell slots, but RAW you cannot use slots for the CON-based casting.

I agree that RAW you can't.

However, the specific wording to allow spell slots to be used to cast spells gained from feats appeared starting with Tasha's, so RAW, I don't think it would work for Magic Initiate or some of the racial ones in XGE either.

That said, as mentioned, ask your DM.

[PhantomSoul]

I'd go against the two above; it still says you learn the spell, so you could cast the spell through your slots. (Compare this to Magic Initiate, where you explicitly have a limit per day.)

"Once you cast it, you must finish a short or long rest before you can cast it again through the mark" (emphasis retained from OP)
Specifies that you can't use the mark to cast it again before taking a rest, but that doesn't block you from using slots, just from the slotless casting (as indicated from the bolded part).