I have broken down each meal you can make with pumpkins to show which one is the most profitable.
Pumpkins 
Buy: 275
Sell: 664
Profit (Per Pumpkin): 389
Veggie Platter, 3 Pumpkins Used 
Buy: at 275 per seed, the buy cost comes to 825 per platter
Sell: 2787
Profit: 1962
Profit Per Pumpkin: 654
Veggie Platter, 5 Pumpkins Used 
Buy: 1375 to buy 5 seeds
Sell: 4115
Profit: 2740
Profit Per Pumpkin: 548
Pumpkin Puffs 
Ingredients: 1 Pumpkin, 1 Egg, 1 Cheese
Buy: 275 + 220 + 180 = 675 total
Sell: 1489
Profit (Per Pumpkin): 814
But what if I add extra pumpkins to the puffs?
Each additional pumpkin added to the puffs only gives an extra 664 coins per puff added, so it is more profitable to turn those extra pumpkins into a separate puff.
Pumpkin Soup 
Ingredients: 1 Pumpkin, 1 Ginger, 1 Milk, 1 Veg (Any)
For this part, we will use lettuce, as it is the cheapest seed to buy
Buy: 275 + 0 + 230 + 3 = 508 total
Sell: 1503
Profit (Per Pumpkin): 995
But what if I use a different vegetable for the "any" veg?
In the table attached I have broken down which "any" veg is the most profitable.
In the end, the most profitable meal is the pumpkin soup, but you are limited in how many you can make by how much ginger you have. All of the ingredients for puffs can be bought. With those two things factored in, pumpkin puffs are the better meal to make.

