Let the unsalted butter, creamy peanut butter and egg sit until they reach 68 to 72°F. Beat the butter with both sugars and peanut butter for 2 to 3 minutes at medium speed, then scrape the bowl halfway through so no dense streaks hide along the sides. Stop there. The mixture should turn a shade lighter and look fluffy but still thick. Beat past 4 minutes and too much air can make the cookies spread wider than you want. Next, check the texture with the spatula. It should hold a soft ridge and smell strongly of roasted peanuts without looking oily. Cream only 2 to 3 minutes because excess air weakens the cookie shape.

Add the egg and pure vanilla extract to the creamed base and beat for 30 to 45 seconds at 68 to 72°F so the fats blend smoothly instead of looking curdled. Then add the all-purpose flour, baking soda and fine sea salt. Fold with a flexible spatula in broad J-shaped strokes for 45 to 60 seconds and scrape the bottom twice. Keep it gentle. The dough should turn from glossy and loose to soft, matte and scoopable. Overmix by another minute and Halloween Peanut Butter Spider Cookies can turn tougher. Meanwhile, heat the oven to 350°F and let the dough stand for 5 minutes. You'll see clean scoop marks instead of wet smears. Fold only until no dry flour remains because extra mixing firms the crumb.

Scoop 1 level tablespoon of dough for each cookie and roll it lightly between your palms for 3 to 4 seconds without squeezing the dough into dense, tight balls. Don't flatten them. Set 24 rounds about 2 inches apart and bake at 350°F for 9 to 11 minutes. Rotate the pans front to back at minute 6 so the edges color at the same pace. The cookies should puff slightly and show fine cracks while the centers stay soft and pale. Go past 12 minutes and the centers lose that tender bite. Look for light golden edges and tops that no longer shine. The middle will still feel soft when touched lightly. Bake 9 to 11 minutes because carryover heat finishes the centers without drying them.

Within 2 minutes of removing the 350°F cookies, press the narrow base of one mini milk chocolate peanut butter cup into each round using one straight downward motion. Press gently. Push only until the candy base sits halfway into the cookie. Then leave the cookies on the pans for 5 minutes before moving them to cool for 20 minutes. The cups should soften at the base but keep sharp ridges around the sides. Press too hard and Halloween Peanut Butter Spider Cookies can split around the center. (I pressed the candy in immediately on one batch. The cups slumped, so the 1 to 2 minute pause matters.) That short pause lets the crumb firm enough to hold the spider body.

Melt the semi-sweet chocolate chips until smooth and let the chocolate cool to 88 to 90°F before decorating. Pipe four uneven legs from each side of every chocolate cup, then add two tiny chocolate dots on the front and press on two candy eyeballs. Keep the lines thin. Let the spiders set for 10 to 15 minutes at 68 to 72°F, then move them to a serving platter with loose natural spacing. Use chocolate above 95°F and it can soften the candy bodies and blur the legs. The finished Halloween Peanut Butter Spider Cookies should have set glossy legs, crisp candy eyes and softly cracked golden tops. Cool the chocolate below 90°F because thicker piping holds the leg shape.