The Great Taste of Pharloom Wish in Hollow Knight: Silksong grants access to another weapon upgrade, but you'll need to find a number of items first. This guide will show you where to find each.
Great Taste of Pharloom is started in the Choral Chambers, in a dining room on the left side of the area. Here you'll find a Pale Oil encased in glass, alongside a sleeping servant. Hitting the glass will wake the man known as Loyal Mergwin, who states that the oil will be used as the final touch for a meal.
Hornet negotiates for the oil, saying she'll collect the ingredient needed for the meal in return. There are 5 ingredients to find, each coming from different sources.
Great Taste of Pharloom Objectives
Mossberry Stew

This one is found in Moss Grotto, in the Mosshome section. There's a small hidden room on the right side, and you'll find the Moss Driud inside here — this is where you can complete the Berry Picking Wish. Talking to the Driud will get you the Mossberry Stew.
Vintage Nectar
Vintage Nectar is in Greymoor, though make sure to stock up on Rosaries. The owner of Halfway Home will sell you the nectar for a whopping 480 Rosaries, giving you access to the cellar below.
When you head down and interact with the glowing item, you'll be attacked by a few waves of ant enemies. You wont be able to get the nectar (or leave) until all enemies are killed.
Courier's Rasher
Perhaps the most difficult of the ingredients to get, the Courier's Rasher is obtained in Bellhart. However, unlike the other ingredients this one isn't an inventory item.
Before you can do this part, you'll have to complete two Wishes from the board in Bellhart: My Missing Courier and My Missing Brother. Once both are done, you can talk to the brothers above the item shop, and they'll have the option to deliver items to different places on the map.
The Courier's Rasher is one such item, which you must take back to Loyal Mergwin. However, you can't use fast travel after accepting the rasher, and it's also rather fragile. It loses freshness over time, with this value going down faster if you get hit, sprint into a wall, or fall from a tall height. If it gets destroyed, you'll have to attempt the trip again by talking to the brothers.
While there are a couple of routes, we've marked the one we took below. It makes use of a number of optional areas, which is also where you can find missing fleas and other collectables.

Crustnut

The Crustnut is found in Sands of Karak, the area above Blasted Steps only accessible once you have the Clawline ability.
Pickled Muckmaggot

The Pickled Muckmaggot drops from an optional boss in Sinner's Road. It requires the double jump ability to access the path up into the boss room.
With every ingredient assembled, head back to Loyal Mergwin to claim your reward.
That's everything you need to complete Great Taste of Pharloom! Make sure to check out more of our Silksong guides below.