In a large bowl, microwave peanut butter and butter until almost melted. Mix well or beat with an electric mixer until combined. Add vanilla and salt and mix until combined.
Gradually add the powdered sugar, mixing with an electric mixer until combined. It will be a little crumbly at this point. Add enough milk so that a soft peanut butter “dough” comes together — it will firm up as it cools so we want it on the softer side.
Press into a 9×13″ pan lined with parchment paper and chill in the refrigerator until cooled, about 30-60 minutes.
Remove peanut butter filling from pan and peel away parchment paper. Use an egg-shaped cookie cutter to cut shapes out of filling. Place on a parchment-lined baking sheet. Rework any leftover peanut butter filling, rolling it into a ball and pressing it into the cookie cutter to make egg shapes with remaining filling. Place baking sheet in the freezer and freeze for 30-60 minutes, until firm.
Make a double boiler to melt your chocolate: place 1″ of water in a small pot and bring it to a simmer over medium-high heat.
Find a glass bowl that fits over the top of the pot and sits on the top edges, but will not touch the water. Add the chocolate and oil to the bowl and place it over the simmering water. Stir often until melted and smooth.
Use a fork to place eggs in chocolate and coat, tapping on the edge of the bowl to remove excess chocolate before placing it on the baking sheet.
Use the same method listed above to melt the white chocolate (no oil necessary). Add in food coloring as desired. Place in a zip-top sandwich bag and snip the end to drizzle over finished eggs.
Store in the refrigerator or freezer until serving.