Biscuits

Overview
Biscuits are Complex Food preferred by Humans, Beavers, and Harpy. Each of your Villagers of these Species that fulfills their need for Biscuits receives a bonus to their Resolve.

Sources and Strategies
Before any Perks are applied, the Recipe for Biscuits in all Buildings yields 10 Biscuits. In any of the 2-star food-production Buildings, the Recipe requires 8 Flour and 3 of any of the flavor ingredients. In the zero-star Field Kitchen, the Recipe requires 10 Flour and 4 flavor ingredients.

For reference, this is the standard Recipe for Flour in a 3-star production Building, like the Rain Mill.

Biscuits are typical rewards from Orders, including Lost Knowledge which rewards 40 Biscuits, 40 Jerky, 40 Pie, and 1.0 Reputation. Also, there are Orders that require Biscuits, but in different ways. If you don't want the Order to take your Biscuits, be sure you carefully read the text and tooltip.
 * One Order requires Biscuits to be delivered from the settlement's inventory.
 * Folks Gotta Eat! requires that 16 Villagers be satisfied by their need for Biscuits and Jerky simultaneously for 120 seconds. This means that you must have the right number of the right Species of Villagers for there to be 16 fed at the same time. It also means that you need to start with more than 16 of each, since you have to sustain the fulfillment for the entire 120 seconds or the timer resets.

Biscuits can be acquired from a Trader. They have a value of 0.25 Amber, therefore a stack of 40 is worth 10.0  to the Trader.

Biscuits are common rewards from opening Caches found randomly in the forest. In the cache rewards tooltip, they are called a 'Basket of Biscuits and contain about 30 to 40 biscuits.

Because the recipe for Biscuits contains Flour, they will not be the first food available to your settlement.

Bare minimum production
If you need Biscuits without a lot of investment, look here. The simplest and lowest-level access to Biscuits from among the ingredients and Buildings still requires two selected blueprints for production Buildings. Altogether, this setup requires 10 Wood, 3 Parts, 10 Planks, and 4 Fabric for the Camps and Buildings.
 * 1) A Root Deposit worked by a Scavengers' Camp AND
 * 2) A Rain Mill, which is slightly cheaper than a Provisioner AND
 * 3) A Bakery which is cheaper than a Cookhouse

Efficient sustainable production
If you need to sustain Biscuits and want to feel efficient at doing so, look here.
 * 1) Farm Fields worked by an Herb Garden producing both Roots and Herbs.
 * 2) The Roots are refined by a Rain Mill into Flour.
 * 3) A Cookhouse or Bakery combines the Flour and Herbs into Biscuits. Since both are two-star, you can choose based on which other products you need.